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Section I. — ^Thb invention op the telescope 7 

Section IL — ^Preluonabt definitions, and optical 
nuNciPLBS to be recognized in the construc- 

Skotion in. — ^Description of common refracting 


The astronomical telescope 26 

The commou refracting telescope for land objects 80 

The Galilean telescope 81 


Manner in which achromatic telescopes are fitted up 

for astronomical observations 86 

Section V. — ^Terrestrial ete-piecb for achromatic 


Astronomical eye-pieces *)Ss 

IMa^ona] eje-pieces *^ 



Section VI. — ^Reflecting telescopes 45 

The Newtonian reflector 46 

The Gregorian reflector 49 

The Cassagrainian reflector 50 

Short accoutU of some large achroinatic and rejlectiiig 
telescopes 52 

Ibices of telescopes, of a moderate size, as made by the 
London opticians 56 

Section VIL — ^Disooyeries which have been made 

by means of the telesoofe. 59 

Discoveries in the solar system 61 

The moon 61 

The sun 62 

Venus and Mercury 63 

Mars 61 

The new planets between the orbits of Mars and 

Jupiter 65 

Jupiter 6S 

Saturn 69 

Uranus 71 

Neptune 71 

Discoveries nnide hy the telescope in the sidereal heavens,.. 72 

The distance and magnitude of the fixed stars 72 

The milky way 73 

Double stars 74 

New and variable stars 76 

Clusters of stars and the Nebulse.. 77 



Beflections suggested by the disooyebies of the 
telescope. 80 

The almighty power of God illustrated 80 

Coincidence between the discoveries of the telescope 
and the representations of Scripture 83 

The cross of Christ a centre from which the Chris- 
tian will survey the universe 84 

Christian revelation viewed in connection with mo- 
dem astronomy 85 



Invention of the microscope 89 

General description of mioroscofes 92 

1. The single microscope 92 

2. The compound microscope 101- 

8. The solar microscope 108 

4. The lucemal microscope 112 

Objects to which the mioboscofb mat be applied 117 
Jinimaleulet 122 

1. The Monads 124 

2. Animalcules in infusions of pepper 125 

3. Eels in paste and vinegar 128 

4. Animalcules in infusions of hay, grass, oats, 

wheat, and other vegetable productions 129 


5. P mciii > U om of some aiuBalcales of 

The pkemomema of blood. 14^ 

OrealMtMm of the blood. 14S 

DeKrijatiam ofAe partt of mme amaU amitmah m Mem w 

Ae auerooeope 146 

1. The flea. ^ 146 

2. Mites 148 

3. CnrioBS species of small cmstaceons animals 150 

4. The stings of animals 152 

5. The hairs of ft-nimalg 152 

6. Scales of fishes 153 

7. The dust on the wings of the moth and butterfly 154 

8. The eyes of insects 155 

Veg^ahle wbttaneet 158 

1. The Carina of flowers 158 

2. The leaves of plants and flowers 159 

3. Transverse sectipns of plants 162 

TutohfecU ^... 167 

Hairs — the bat, mouse, dermestes 167 

Scales on the wings or bodies of insects 169 

Comparison of the ioorka of nature <md art. 170 

Method of uamg miero9cope$ 173 

REFLEcnoirs 176 

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God has been pleased, in various ages, to guide 
men to those discoveries which have enlarged 
their views of his perfections, and increased their 
knowledge and happiness. Among these dis- 
coveries may be placed the construction and the 
uses of the telescope. 

Section I. — The invention of the telescope. 

The telescope is an instrument for looking at 
distant objects. Its name is compounded of 
two Greek words, tele, at a distance, and scopein, 
to view. {TrjXe, aKonelv,) By this instrument, 
the most distant objects seem to be brought near 
to the eye ; and many of those which are obscure, 
and without its aid invisible, are clearly seen. 
A terrestrial object, at the distance of six miles, 
is as distinctly visible as if it were within eighty 
or a hundred yards ; and wotlda, '^VkO^^^'^^ Vs^ 



ages conceialed in the remotest depths of sfpoe, 
or irhich shbe only as luminous points^iS the 
heavens, are made so acci^ssible to our sight, that 
thrar appearance, magnitude, and movements, 
may he described and calculated. 

It is difficult to determine to whom we are in- 
debted for the telescope, and what is the precise 
date of its invention. No discoveries have been 
handed down to us, which would lead to the 
conclusion that it was known to the ancients. 
Before the end of the thirteenth century, glass 
lenees were used to assist the eye in ohtainiug 
distinctness of vision. There can be uo doubt, 
also, that the celebrated Roger Bacon, who died 
in 1292, was aware that lenses might be so ar- 
ranged, as to magnify the appearance of objects 
seen through them ; but there are good reasons 
for beliering, that his knowledge was derived 
only from reflection, and tliat he never carried 
Ilia theory into practice. Whatever were the 
ideas, or the eipeiiments of the learned, the teles- 
cope was not much known before the beginning 
of the seventeenth centui?. If, as some have 
supposed, its existence may be traced back to a 
much earlier period, its importance was not dis- 
covered until an accidental circumstance brought 
ronderful power into public notice. The 
of a spectacle maker, residing at Middle- 


burgh, in Holland, were playing in their fath( 
workshop, and observed, that when they h« 
between their fingers two spectacle glasHes, 
some distance one before another, and looti 
through them at the weathercock of the church, 
it seemed inverted, but very near to them, 
greatly inRreased in size. Having called the at- 
tention of their fatier to this strange sight,* lie 
adjusted two glasses on a board, supporting 
them on two brass circles, the distance of which 
from each other might be increased or dimiDished 
at pleasure. Many persons visited Ms workshc 
to see liis experiments, which afforded ami 
ment, and awakened curiosity. To this iucidc 
we may probably attribute the expresidon 
Huygons, an astronomer of the seventeenth 
tury, who described the telescope 

For some time the oontrivance of the Middle- 
burgh optician remained unimpro\-ed, and was 

" The samo change in the appearauce of olueotB tc 
be »een by atij one wlio haa (c1b3?cb at command. ~ 
a oonvex glasa or lens. Buppass of fourteen inohes t 
eil distance, and another of two iochea focal distau 
Jiold theia in a lltii) sixteen inches agunjBT, and In 
thTOugh the glass of two inclwa fooua, and objeotB will 
appsar inverted, and seven limes larger and nearer 
than to the naked eye, that is. in the propartian of 
fbttKeeu to two. 



tH will I 


applied to no valuable purpose. At length, 
about the year 1609, two workmen of the same 
city, by giving to his discovery a new form, made 
all the honor of it their own. Tlicse men, whose 
naraes were Zachariah Jans, or Jansen, and Hans 
Lapprey, or Lippersheim, are said to have beea 
spectacle makers. One of them placed the 
glasses in a tube, the inside of which he blackeced, 
to prevent the glare, which would be occasbned 
by the reflection of light from a bright surface, 
and which would produce indistinctness of vision. 
The other placed the glasses in tubes, sliding one 
within another, to make the instrument portable 
by diminishing its length. When Jansen had 
completed his telescope, he presented it to Prince 
Maurice of Nassau. The United Provinces were 
then at war with Fmnce, and the prince, per- 
ceiving the advantage which he might obtain in 
the field over the enemy by means of this gift, 
desired that its invention should be kept a pro- 
found secret. But the time had now arrived when 
the telescope was to be employed for nobler pvtr- 
poses than those of war, and, ba the medium of 
. most astonishing discoveries, to j astify what soon 
afterwards was said of it, that the wit and indus- 
try of man bad produced nothing so worthy of 
his faculties. (Huygens.) 

Before the time of Oalileo, who was born at 

Pisa, in 1564, the obsei'vations which had been 
made on the heavens were few and imperfect. 
He has been frequently supposed to be the in- 
ventor of the telescope, beeanse he was the first 
who successfully applied it to astronomj'. In the 
following passage, translated from a small work, 
■written in Latb, which be publbhed in 1610, 
under the title of " S'ldereui NKTirini" he con- 
futes this notion, and. shows what prompted hie 
first efibrts to make such an instmment. " Nearly 
ton months ago, it was reported thiit a certain 
Dutchman had made a perspective, throiigli 
which many distant objects appeared as distinct 
as if they were near. Several eiperimenta were 
reported of this wonderful effect, which some be- 
lieved, and others denied ; but, having had it 
confirmed to me a few days after, by a letter 
from Paris, I applied myself to consider the rea- 
son of it, and by what means I might contrive a 
like instrument, which I attained to soon after 
by the doctrine of refraclions. And, first, I pre- 
pared a leaden lube, in wLose extremities I fitted 
two spectacle glasses, both of them plane on one 
Bide, and on the other side one of them spheri- 
cally convex, and the other concave. Then, ap- 
plying my eye to the concave, I saw objects ap- 
pear pretty large, and pretty near me ; they 
peared three times nearer, and mne times 


in surface, than to the naked eye. And soon 
after I made another, which represented objects 
abore sixty times larger; and at last, having 
spared neither lahor nor expense, I made an 
inEtcument so excellent as to show things almost 
a thousand times larger, and about thirty times 
nearer, than to the naked eye." 

When Galileo had finished his best telescope, 
he directed it first to the moon, the nearest of 
the heavenly bodies, and saw it, as he Bays, at a 
distance within two diameters of the earth. He 
perceived on its surface tvfo kinds of spots, one 
very clear, and the other dusky, resembling 
clouds. He also remarked, that the boundary 
between its dark and enlightened parts was ne- 
ther a straight line nor a regular curve, but that 
it was jagged and uneven, indicating the existence 
of mountains and valleys. On esamining the aun, 
he discerned several large dark spots, and ascer- 
tained from their motion across its disc, that it 
revoived round its axis in about twenty-sii days. 
Jupiter presented to I'im new wonders. He 
perceived three small stars close to the line in 
which it was moving. By subsequeflt observa- 
tion, he sow that they frequently changed then- 
position, and sometimes disappeai'ed. After 
watching them for a long time, he found tha' 
they -were amaU planets, revolving roimd tht 

laiger one, as the moon revolves round the earltk' 
He afterwards discovered ti fourth eateltite. 
Looking through his glass at Satum, he was as- 
tonished to find it had the appearance of a planet 
of large dimensions between two araailor ones. 
They seemed almost to touch each other, and to 
have their centres in a straight line. This obser- 
vation was made early in 1610. GaUleo was 
etill more astonished in 1612, to find that the 
two smaller planets had disappeared. About 
ten months afterwards tbey were again visible. 
They soon assumed various shapes, and were 
sometimes round, and then oblong ; at other times 
semicircular, and then lunar, with horns pointing 
, inwards, and growing by degrees so long, and bo 
wide, ns nearly to encompass the 
middle. To some the three appeared to be 
jiuned, and to others to be disunited. Consider- 
ing the imperfection of the first telescopes, it is, 
perhaps, cot surprising that more than forty 
years elapsed before any satisfactory esplanalion 
cotdd be given of these phenomena. In 1650, 
Huyg;ens published his dieuovery, that SntiuTi is 
Burroundcd by an immense ring, the two lateral 
parts of which had been erroneously supposed 
to be two Binaller planets. In his desoriplion 
("Systema Satumium") of it, he established 
the position of the ring, ani exi 


ite.. ■ 

ider- ^^B 


of its occasional disappearance, and of the dif- 
ferent forma under wbich it is seen. Venus waa 
the next object wMch. engaged tbe attention of 
Galileo. He observed this planet when near its 
superior conjunction. At first it looked nearly 
globular ; shortly afterwards Its phase was gib- 
bous, or defieient in roundness ; it quickly became 
lunated, or like a half moon, and then it dwindled 
into a slender crescent, like the moon when three 
or four days old. From these observations he 
coDcluded, first, that the planets are opaque 
bodies like the earth and moon, deriving all thor 
lights from the sun ; and, secondly, that Venus 
moves round the sun, and not, as was geuerally 
imagined, round the earth. He then examined 
the fixed stars, and beheld many, invisible to the 
naked eye, nearly as large as those of the first 
and second magnitude. Within the range of 
the Pleiades, he counted no less than Ihirty-sis 
stars, and almost as many in the constellation of 
Orion, which are not visible to the unaided sight. 
Prsesepe, which looks but a dim speck in the 
sky, he perceived to be a cluster of forty stars, 
and the Galaxy, or Milky Way, to be an innu- 
merable multitude, powdering* the heavens ivilh 

° " The gulttKj, that milky way, 

Which nightly, as a circtiue loue, thou Meat 
Poirdtr'd with stans." Mii,tob. 

Uglit. The doubts of former philosophers re- 
•pecting thb remarkable tract were at once solved, 

' many of their speculations respecting it were 
•kown to be scarcely less nhsurd than the fables 
of the mythologists. 

Intelligence of tfao discoveries of (JalUeo ra- 
'jiidly spread throughout Italy and other Eu- 
lopean countries. His book, already mentioned, 
«Blitled " Sidtreut Nundug," produced an ex- 
tiacM^nary seusation amon^ the learned. His 
•tatemente were opposed to tlie philosophy of 
Anstotte, and that was a sufficient reason with 
many for their rejection. Some endeavored to 
NftBon against hb facts, but others satisfied 
with asserting, that such thin, 
and could not possibly be. The prinoipat^ 
Hufeasor of philosophy at Padua, lest he should 
)e convinced of their reality, refused to look 
lltroi^h the glass of Oahleo. Martin Horicey, 

ither of his opponents, is reported to have 

1 to Kepler,* " I will never concede his four 

Miltou riaitcd Galileo, and entertained the liigheat 
l^idon of his phiiuaopb;, to nhicL he mokes some 
bwutiful allnsiooa in his " Paradise Loil." 

An able mnthematiciaii and aatrgnomer. Ro waj 
I at Weil, in the dnobj of Wirttmberg, in IflTl, 

died in ItiUO, Between him and Oalik>o tlw , 
mest frieadsbip aubsiated. 

new planets to tbat Italitin from Padua, tliough 1 
I should die far it ;" tmd in n book wbich he 
published he solemnly decliired, tbat he did not 
more surely know that he had a soul in 
body, than thnt reflected rays were the entire 
cause of Galileo's errors. Sizzt, a Florentine 
astronomer, reasoned in this way: "Tiierc are 
seven windows given to animala in the domicile 
of the head, through which the mr is admitted 
to the rest of the tabernacle of the body, to 
enlighten, warm, and nourish it ; two nostrils, 
two eyes, two ears, and a mouth; so in the 
heavens, or the great world, there are two fa- 
vorable stars, two unpropitious, two luminaries, 
nnd Mercury alone undecided and indiSerent. 
From which, and many other similar phenomena 
in nature, such as the seven metals, we gather 
that the number of the planets is nteenaarily 
seven. Moreover, the sateUites are invisible to 
the naked eye, and therefore can eiejt no in- 
fluence over the earth, and therefore would b6 
useless, and therefore do not exist." An agree- 
able contrast to this senseless bigotry is presented 
in the conduct of the senators of Venice, who 
were eminent for their learning and palriotbm. 
They invited Galileo to their city, to make a 
trial of his new insti'ument in their presence. 
Having complied with thuir invitaticm, one fine 


bight, neither cold nor cloudy, he erected his 
telescope on the top of the tower of St. Mark. 
Jupiter was shinbg brightly on the meridian, 
the moon wus displaying its silver horns towards 
the west in the form of a crescent, and Venus 
was in full sjikudor in the same direction. The 
senators gathered round the astronomer. Jupiter, 
with its three satellites, the fourth being eclipsed 
by the body of the planet ; Venus, at its farthest 
distance from the sun, not a completely illu- 
mined sphere, but one-half obscured ; and the 
crescont of the moon, with its internal moun- 
talnous -looking border, passed in succession un- 
der their review. The senatoi's acknowledged 
the truth of Galileo's discoveries, and alternately 
poured upon him their compUments, and pressed 
Hm with their inquiries. When he had answered 
all their questions, he delivered a long lecture 
to his distinguished auditors on the true system 
(rf the universe. He showed that die ancient 
system of Piolemy could not be reconciled with 
the motions of the heavenly bodies, and that 
the changes of day and night, the revolutions of 
the seasons, the precession of the equinoxes, and 
other phenomena, could only be explained on 
the theory of Copernicus. That night was fatal 
to the system of the ancient schools, The ad: 
mirable discourse of Galileo camei torn 

to every mind, The Venetian noble 
ledged the pei-fect agreement of all thoy had 
Been ■with the Copemicnn system.* From this 
time it began to obtain credit throughout Eu- 
rope, and the improvement of the telescope 
became important to all who appreciated these 
early fruits of its invention. 

Section II. — Preliminary dejimtionit, and opti- 
cal principles to be recognized in the construe' 
tion of the telescope. 

It b not necessary to enter iuto what Ts ab- 
struse in optical science, in order to understand 
the general principles on which a telescope is 
constructed. But there are certain facta re- 
specting light, and it« I'efractions, rcBectJcinH, 
and their effects, of which some information may 
be useful. 

Light is an ethereal matter, distributed 
throughout the universe, and rendering per- 
ceptible to the eye Bcenes and objects, at once 

" Copernioua was bom towarils the close of 0» 
fifteeuLh centarj, at Thoni, in Pruasia. In his ty»- 
tern he mode the sun the centre, about whioh the 
planets reTolve at difTercDt distftsces, anil vith dif- 
ferent degiTCB of Tolocitj. Above Ihe plnneta he 
placed the BtBrry hcuvciia. whiuh are boundloB and 

the nearest and the most remote. It is essential 
to life and happmeas. Wkliout it, creation 
would be lifeless and unadorned. Like a per- 
vading spirit, it animates what it reveais. It 
faas become associated in our minds with order, 
lieBuly, and goodness. It is so glorious, that it 
is said to be the "garment" (Psa. civ, 2) of the 
Almighty. It is so pure, that it is an emblen 
by which He himself is represented. 1 John 
It is so transforming, that light ia the written 
name of that new creation, which It ia the wodt' 
of the Holy Spirit to acconnplish in the heart of 
man. Ephes. v, 8. 

As the properties of light form the foundatioti 
of the structure of the telescope, some of these 
may be briefly stated. 1 . Light emanates or 
radiates from luminous bodies, when passing 
through the same medium, m a fitralifkt lint. 
This ia proved fay the impossibility of seebg 
light through bent tubes, or small holes pierced 
in metallic plates, put one beliind another, unless 
the holes be placed in a straight line. 2. The 
particles of light are almost infinitely small. Dr. 
Niewentyt computed that more than six billion 
times as many particles of light flow from a 
candle in one second of time, as there are grains 
of sand in the whole eartlij supposing each cui^ 
incli of it to conlaiu Dn-e- niffi'tfnt. 





moves with amadng velocity. It tmvels a 
llie earth's orbit, a space of 100,000,000 of miles 
in extent, in the course of sixteen and a half 
minutes, or at the rate of 192,000 miles every 
second, which is more than a million Umes 
swifter than a cannon ball flying with its utmost 
velocity. 4. Light is sent forth in all directions 
fifom-evcry visible point of luminous bodies. If 
we hold ;i sheet of paper liefore the sun, we 
shall find that the paper is illuminated in what- 
ever position we hold it, provided the light is 
not obstructed by its edge or any other hotly. 
5. It is by light reflected from opaque bodies 
that most of the objects around us are rendered 
viable. When a lighted candle is brought into 
a room, not only the candle, but all the other 
bodies in the room become visible. In like 
manner, the light of the sun falling upon the 
moon and planets, which are opaque bodies, is 
reflected from their surfaces, and renders them 
visible to oiu' sight. 

When the ravs of light continue in any me- 
dium of uniform density, tbey proceed in straight 
lines, but when lliey pass Miqutl;/ out of one 
medium into another, which is either more dense 
or more rare, they are refracted towards the 
denser medium, and this refraction is more or 
|H| aft the rays fall more or less obliquely on 


refraclisg surfaoe which divides the mediunnB. 
This may be illustrated by fig. 1, where b o is 
the incident ray which falls upon the medium 
N o, which suppose to be water ; c b is the re- 
fracted ray, d a the perpendicular, a a the sino J 
of the angle of incidence a o d, and n r the sine J 
of the angle of refraction e c e. Now it b a 
|iroi>oeitioii in optics, that the gine a d of the 
angle of incidenco a c d, is m a given proportion 
to the sine h b of the angle of refraction o o e. 
Th« ratio of the shies is as four to three, when 
tie refraction is made out of air into water; that 
iSiAoiatonaas four to three. The angle 
which the incident ray makes with the perpen- 
, dicular is called the anffle of incidence, and the 
angle which the ray makes with the same per- 
pendicular after it eaters the medium, is called 
the angU of refraction. If a ray of light n ^~ 



were to pass from air into water, or from empty 
space into air, in the direction m c perpendicular 
to the plane n o, which separates the two me- 
diums, it would suffer no refraction, because one 
of the essentials to that effect is wanting, namely, 
the obliquity of the incidence. 

It is to the refraction of light that we are in- 
debted for the use of lenses to aid the powers 
of vision. A lens is a transparent substance, 
usually glass, having two surfaces, either both 
spherical, or one spherical and the other plane. 
A convex glass is thick in the middle, and thin- 
ner towards the edges. A concave glass is thin 
in the middle and thicker towards the extremities. 
Of these there are various forms. In the annex- 
ed fig. 2, A is a plano-convex, b a piano- coii- 
cave, c a double convex, d a double concave, s 
a meniscus, or concavo-convex, which is partly 
convex and partly concave, the convex side beii^ 
a portion of a smaller sphere than the concave. 

The rays which proceed from visible objecte 
are either parallel, converging, or diverging.' 
Parallel rays are those which are equally dia^; 
tant from each other, as those which proceed 
from the sim and planets, and from distant ter- 
restrial objects. Converging rays are such as 
approach nearer and nearer in then* progress to 
a certain point where they unite. Diver^ng 



Fig. 2. 



Double convex. 

Double concave. 

Meniscus, or concavo- 

rays are those which continually recede from 
each other, as the rays which proceed from near 
objects, such as a window in a room or an adja- 
cent house. 

When a convex lens, whether piano or double 
convex, is placed opposite to any object, the 
rays of light which pass through it form an 
image or picture of the object in its focus, if a 
paper or card be placed to receive it. Let l n, 
fig. 3, represent a double convex glass, a c its 
axis, and o b an object perpendicular to it. A 
ray passing from the extremity of the object at 
o, after being refracted by the lens at f, will 
pass on in the direction f i, and form an image 

of that part of the object at r. In like niitnner, 
B t M is the axis of that parcel of rays which 
proceed from the extremity of the object d, and 
their focus will be at li, and all the points of the 
object between o and b will have their foci be- 
tween i nnd m, and an image of the whole object 
o B will be depicted in an inverted position, be- 
cause the rays cross at c, the centre of the lens. 
This may be illustrated by experiment. Tabe a 
coiivex glass of eight or ten inches focal dis- 
tance, a reading glass, for example, and holding 
it at its focal distance from a white wall, m s 
line with a gas lamp or burning candle, the flame 
of the candle or lamp will be seen painted on 
the wall in an inverted position. The fact novr 
staled is an important principle in opiics, and 
forms the foundation of the camera obscum and 
of the telescope. 

The property of forming exact representatJons 
of the objects from whence its rays proceed is 


possessed by light, whether emanating direc^ 
from the sun, or reflected from the objects it 
illuminates, or coming from bodies artificially/ 
enlightened. This property ia hght is not p 
liar to the system to which we belong, 
were, our field of vision would Lave beep' 
paratively limited. The telescope worild have 
been useless for the observation of.tfioae distant 
stars, which are the suns of otbeHyst«ma beyond 
our own, and we should linv'e remained in pro- 
found ignorance of worlds, " in number beyond 
number," which now "declare" to iia "the 
glory of God." In this point of view, we can- 
not regard as accidental an inveation which has 
made us better acnuainted with his omnipotence 
and wisdom in the existence and arrangements 
of the universe. It reveals to ua hia providen- 
tial care displayed in all the departments of 
nature, In every ray of light it teaches us the 
lesson that " God is love." It leaves us, how- 
ever, to learn from another source the highest 
manifestations of that love. The Bible alone 
can tell us that " God so toved the world, that 
he gave his only begotten Son, that whos 
bcUereth in him should not perish, but 1 
r everlasUnglife." John iii, 16, 

Before describing the structure of a ti 
may be proper to state the manner a 


the fooal diEtance of a convex lens. Le«^ 
fig. 4, be a convex lens, and c d parallel 

proceeding from the sun ; those raya, afterpaai 
ing through the lens, will converge to a point 
Hold the lens opposite to the rays of the svo 
and observe where the rays converge to a erne 
spot as at e. This spot is the image of the sv 
formed by the lens ; measure the distance b 
tween the lens and the spot; it is the focal di, 
tance required. 

Section III. — Description of common re/ractin 

There are various kinds of refracting tel< 
scopes, which we shall describe in their orde 
commencing with that which is the most simpl 
and most easily understood. 

1, T/ie astronomical telescope. — Theonlypan 
essential to this telescope are two lenses, a 


Fig. 5. 



and £ Ty fig. 5. A d is the object-g^M, and 
E T is the eye-glass. Let o b be ^/distant ob- 
ject, from which rays proceed jeroarly parallel 
to A D, the object-lens. The rays passing through 
this lens will form an image of the object in its 
focus at I M, and as the rays cross each other it 
will be inverted, e y, the eye-glass, is placed 
exactly at its focal distance from this image, and 
must be of^a much shorter focal distance than 
the object-glass. The magnifying power in this 
telescope is in the proportion of the focal dis- 
tance of the object-glass to that of the eye- 
glass. Suppose the object-glass to be of twenty- 
four inches focal distance, and the eye-glass one 
inch, the magnifying power is then as one to 
twenty-four ; in other words, it makes a distant 
object appear twenty-four times nearer, and 
twenty-four times larger in size than it is to the 
naked eye. If the eye-glass had been one and 
a half inch focal distance, the magnifying power 
would have been only sixteen times. Through 
this telescope all objects appear inverted, like 
the image at i m. This telescope was much in 
use by astronomers in the sevciv^e^tLXXi «x^^. 


eighteenth centuries. In order to obtaia ^ ^ 
dderable magnifying power, it was soorke^' 
m^e more than one hmidred feet long ; anr 
it was found inconvenient to have a tube of 
length^"tt^ telescope was used without one. 
high poleVwas erected, the object-glass 
placed at th^op of it, and capable of b^^I 
turned in every \direction by a cord whfcfi 
descended to the station occupied by the ob- 
ser^-er, who held the eye-piece at the height 
of his eye, resting it on a pedestal. But these 
long instruments are now entirely superseded by 
the invention of achromatic and reflecting tele- 

A telescope of the kind described may be 
easily constructed, and at a small expense. Pro- 
cure a double convex lens, about thirty-six 
inches focal distance, place it at the end of a 

Fig. 6. 


tube, as at a b, fig. 6 ; at thirty-seven inches 
distance from this glass fix another, c d, whose 
focal distance is one inch. This glass must be 
fixed in a separate shoil; tube, e f, which should 
be made to slide backwards and forwards in the 
large tube, for the purpose of adjusting the 


focus of the telescope to the eye. Such a tele- 
Bcope will magnify objects in the proportion of 
one to tbirty-aix, or thirty-six times, and will 
show the spots in the sun, the shadows of the 
mountains and cavities in the moon, Jupiter's 
satellites, the crescent of Venus, and otiier celes- 
tial phenomena. In constructing such a tele- 
scope, the following particulars require to be 
attended to ; — 1. The aperture, or opening which 
lets in the light at the object-glass, should not 
exceed one incli in diameter, otherwise the image 
of the object will be somewhat confused. 
2. There should be a hole or aperture in th« 
focus of the eye-glass rather less in diameter 
than the breadth of the cyc-glass, for the pur- 
pose of excluding .the exttaneous rays. Were a 
telescope of this kind to be constructed with an 
object-glass six feet focal distance, the eye-glass 
would require to be one and a half inch focal 
distance, and the aperture of the object-glass 
one and a half inch diara«ter, and the magnify- 
ing power would be forty-five times. Were the 
object-glass ten feet focus, the eye-glass would 
require to be one and nine-tentha inch focus, 
the aperture one and seven-tenth^ inch, and 
magnifying power would he siitj-three timt 
Were the object-glass twenty feel focus, the 
glass would be two and a UaVl WVa* Wraa- 





jiperLwe two aiid four-tentlis, and the m 
ing power would be eighty-nine times, 
fonnd, that in order to magnify twice as maeh 
Bs before, with the Batoe light and distinctnesB, 
the telescope must be lengthened four times; to 
magnify three times as much, nine times i fojle 
times Hs much, siiiteea times ; that ia, suppb^ft 
telescope of three feet to magnify ihirty-mi 
&tiea, in order to procure a power four times u 
greatj-or one hundred and forty-four times, we 
muBt cjctend the telescope to the length of forty- 
eight feet, or sixteen times the length of the 

2. The common refraclijfff' tcleacopf for lattd 
olgeeta. The telescope just described, in coo- 
sequence of its shon-ing every -^lAject m an in- 
verted position, is not fitted for land objects. 
In order to adapt it for terrestrial objects two 
Additional eye-gkssea are req.nired. In fig. 7. lei 
o B represent a dbtant object, i. k the object- 



glaw which forms the image of i m in an inverted 
poeition ; let e e represent another glass placed 
M its focal distance from this image, as in the 

' \ 


V^ .otaical telescope, and f f a second glass, 
'^Sced at twice ite focal distance from e e. By 
this glass (f f) a second image is formed at i m, 
contrary to the first image i m, and, consequently, 
erect. This last image is viewed by the third 
lens, a G, in the same manner as the first image 
I M would be viewed by e b. All these eye- 
glasses are understood to be of the same focal 
distance, and are placed at double their focal 
distance from each other. Such a telescope 
represents land objects in their natural positions. 
But this arrangement of glasses is different from 
the eye-piece now adapted to achromatiq tele- 
scopes, of which we shall afterwards give a short 

3. The GcdiUan telescope, — This telescope con- 
sists of two glasses, a convex glass, c, next the ob- 
ject, and a concave, k, next the eye, fig. 8. Let 

Pig. 8. 

I D represent rays proceeding from an object ; 
tliese rays would converge to their foci, and form 
m inverted image at f, if they were not intercepted 
by ^ ooikoaye lens k. But tVfi& \«c& \a^\s^% ^ 


double concare, occasions the rays to <ii'v»n 
more than before, so that the rays d i ^^aruitu 
from the object, instead of converging to j^ jv 
made to proceed parallel to o h, and it is para 
lei rays that produce distinct vision. The coi^ ' 
cave lens, k, is placed as much within the foc^^ 
distance of the convex, c, as is equal to its ow^ 
focal distance, and the magnifying power, ai 
formerly, is in proportion to the focal distance 
of the object-glass to that of the eye-glasa 
Thus, suppose the focal distance of the objeotf 
glass to be twelve inches, and that of the con- 
cave eye-glass one inch, the concave must b6 
placed at eleven inches from the object-glasi^ 
and the magnifying power will be as one to 
twelve, or twelve times. . This was the land of 
telescope constructed by Galileo, and with which 
he made his astronomical observations. Objects 
are seen through this telescope in their natural 
position, and very distinct, even more so than ii 
other telescopes ; but the field of view is so very 
small that its use is almost exclusively confined 
to the common opera-glasses. A good telescope^ 
however, can be made on this principle capabla 
of showing much to interest the observer. If 
we take a convex lens, forty inches in focal dis« 
tance, we may apply to it a concave lens of onl^ 
one inch focal distance, at the distance of thirty!: 

lune inches from the object-glass, and the mag- 
nifying power will be forty times, which will 
show us Jupiter's satellites, the crescent of Ve- 
nus, and Saturn's ring. There is some difficulty 
in finding on object with this telescope, and only 
ft pnrt of the sun and moon can be seen tbrougti 
it at one time. 

Skction IV. — The achromatic teleseopc. 
The common astronomical refracting telescope 
was very imperfect, and "was also so unwieldy 
that its use .was attended witli much trouble and 
inconvenience. To obtain a considerable magni- 
fying power, it was found necessary to increase 
its length to siity, eighty, one hundred feet, and 
upwards. To get a power, for example, of 
about two hundred times, the telescope requli 
to be one Iiundi'ed and twenty feet in ]engtit. 
Its other imperfections consisted, — J, in t1 
rays of compounded light coming to their foci 
difi'erent distances from the glass. Every ray of 
light, as is found by the prism, is compounded 
of various colors, and these have different foci, 
the more refrangible, aa the violet, converging 
sooner to ii point than those which are leaa re- 
frangible, as the orange and the red. Hence the 
image of an object formed by a single lens is in 
some degree confused and tndisttacb,a,'ad.,^^'(A- 




fore, will not bear to have a high, powier pt 
upon it. 2. Another imperfection was this, tin 
spherical surfaces do not refract the rays of ligl 
accurately to a point. The rays which pai 
near the extremities of such a lens meet in fo^ 
more distant from the lens than those which pa%^ 
nearly through the centre, and hence are invar^^ 
ably colored. 

To remedy these defects is the intention of the 
achromatic telescope, the theory of which 
first made known by Mr. DoUond, an optioi 
of considerable celebrity in London. • The objeet- 
glasses of this telescope are frequently composel 
of three distinct lenses, two of which are convex . 
and the other concave. The two which are cofr 

Fig. 9. 

vex are made of London crown>glass, and tb 
middle one of white flint-glass, or that kind cf 
glass of which wine-glasses and tumblers iii 
made. Fig. 9 represents this compoimd triplB 
object-glass, as it is fitted up in its coU, airi 


placed H.I the object-end of the telescope. 
it is now more frequently the practice with 
IJoiane to form this object-glass double, 
fig, 10, where * h is the conrex of urown glass, 


Use ^* 


And C » the concave of flint glass. The oonvei 
is placed outside next the object, and the con- 
care in the inside. By this combination of 
passes, when accurately adjusted to each other, 
an image of the object is formed without being 
bimded with the piismatic colors. Hence the 
word achromalic, by which this telescope is dis- 
tinguished, signifies free of color. In conse- 
quence of this property, such glasses will bear 
B much larger aperture, and a much greater 
magnifying power, than common refracting tele- 
seo]}es. While a common telescope, whose 
object-glass is three and a half feet focal dis- 
tance, will scarcely bear an aperture of one inch, 
the three and a half feet achroraalic telescope 
will bear the aperture of three and a quarter 
inches, and. consequently, will transmit more 
tlUm ten times the quantity of light. White H 
bear a magnifying power oC wiVj *^ 


six times, the other will bear a magnifying 
for astronomical purposes, of at least two ^^n^u 
dred times ; so that a good achromatic iele^copi^ 
only four or five feet m length, will carry a 
power equal to one of the common construction 
one hundred feet long. 

Manner in which achromatic telescopes an 
fitted up for astronomical observations. — r, in fig. 
11, is the body of the telescope mounted on a 
tripod pedestal of brass, a is the eye-pieoe, 
which screws off to admit other eye-pieces to be 
applied, e is the long eye-piece for terrestrial 
objects. D is an astronomical eye-piece, b con- 
sists of two or three sliding tubes of brass, for 
rendering the instrument steady ; and a is a brais 
knob, which moves a piece of rack work for 
adjusting the focus, a h the finder. 

This telescope is now generally used. If 
flint glass of a large diameter, and without 
blemishes, could easily be procured, it woild 
soon supersede almost all other telescopaft 
But hitherto it has been very difficult, in Britaki» 
to procure large discs of flint glass, of a good 
quality, imless at a great expense. We have 
been chiefly indebted for the largest discs of 
flint glass, and for the best achromatic telescopv 
we possess, to the French and Germans, wbft 
charge high prices for such articM. But m 

ic prospect, that glass for achromii- 
aes may be procured Id greater abund- 
at a more moderate cost, than Tormerly. 
achromatic object-glnsa is prepared, 
I in a tube, we apply magnifying pow- 
in the same way as to the common 
; only we can ti.>fV% \o '*. ft^e.-^»»»«» 


>f a much shorter focal distance — such 
or quarter of an inch — than we can app] 
object-glass with a single lens. But as i 
piece for achromatic telescopes is difFere 
that formerly described, it may be expedi< 
to give a short description of it. 

Section V. — Terrestrial eye-piece for ack 


This eye-piece, which is represented in 
consists of four lenses, combined on th 

Fig. 12. 

ciple of a compound microscope, a i; 
ject lens, or that which Is next the ol 
the amplifying lens, c the field-lens, 
eye-lens, or that next the eye. At 
formed near the glass a by the ol 
From the image a second is formed ? 
i, in the same position as the object. 
at i might be formed by the lens a, 
not be well-defined, owing to the gr 
aberration, and therefore the lens i 
a little distance beyond the focus 
diaphragm, having a hole of a sr 



o A, at the focus of a, to cut oflf the colored 
rays. The glass c is intended to enlarge the 
field of view, and the image at i is viewed by 
the eye-glass d. At the place where the second 
image is formed, there should be a stop, m w, 
to prevent any false light passing through to the 
eye. As to the focal distance and arrangement 
of these glasses, suppose the lens a one and 
seven-eighth inches focal length, b may be two 
and a half inches, c two inches, and d one and 
a half; and their distances a b two and a half, 
B c three and five-eighths, and c d two and three- 
eighths. In a small pocket achromatic telescope, 
whose object-glass was eight and a half inches 
focal length, and its magnifying power fifteen 

and a half, the focal lengths of the eye-glasses 
were found to be, a 0.775 of an inch, b 1.025, 
c 1.01, D 0.79 ; the distances, a b 1.18, b o 
1.83, and c d 1.105.' This eye-piece would be 
nearly equivalent, in magnifying power, to a sin- 
gle lens of half an inch focal distance. 

For the sai^e of those young persons who may 
wish to construct an eye-piece of this kind, I 
shall state the dimensions of one or two in the 
possession of the writer. In one of these, 
adapted to an achromatic object-glass five feet 
three inches focal distance, and four inches dia- 
meter, the lens a is three inches focal length, 


plano-convex; the plane side next the a 
three and a quarter inches, c one and &^^ 
eighth inches, d one and a quarter inches. 'I^^^* 
are all plano-convex, with the plane sides ^^^ 
the eye except the lens a. Their distances an^ 
A B three and three-fourths, b c five and three- 
fourths, c D two inches. This eye-piece is eleven 
and a half inches long, and produces a magni- 
fying power for land objects of about ninety -six 
times. The tube containing the two glasses next 
the eye, c and d, being taken out, a tube con- 
taining other two glasses is inserted, the focal 
distances of which are, c two and a quarter 
inches, d two inches, and their distance three 
inches. This, in combination with the other 
glasses, produces a power of about sixty limee^ 
If the glasses, c n, be placed in a movable tuhe» 
c e^ a 6, by pulling out this tube, and conse- 
quently increasing the disUince between b and d 
the magnifying power may occasionally be in- 
creased to one half, or nearly double what it had 
in its original state. On this principle, Edich- 
ener's Pancratic eye-tube is constructed. 

Astronomical eye-pieces, — The combination of 
lenses now most frequently used for astronomioii 
observation is that which is denominated tUn 
Huygenian eye-piece, which is a great improre- 
ment on the eye-piece with, a &u\^le leua, aa it 

cil of wliite liglit proceeding from the object- 
glass, B p a pi uno- field-glass, with its plane side 
next the eye-glass e. The red rays of the pencil, 
A B, after refraetioD, would cross the axis in r 
and the violet mys in v, but meetJag the eye- 
glass E, the red ra}'s will be rei'racted to o, and 
the violet nearly ia the same direction, when 
tbey will cross each other about the point o in 
the axis, and unite, so as to form an eye-piece 
almost without uobr. Tlie distance of the two 
glasses, f &, to produce tliis correction, must be 
equal to half tiie sum of their focal distances. 
Suppose the focal distance of the field-lens r to 
be three inches, and that of k, the lens next the 
eye, one inch, the two lensea should be placed 
exactly at the distance of two inches ; in other, 
words, the glass next the eye sliould be pla< 
lis much wUhin the focwa ol ft\c ti^V^s^ 




equal to its own focal distance. The focal lex^-o^ 
of a single lens that has the same i^SLgrn^yrnur 
power as this compound eye-glass, is equal to half 
the focal length of the field-glass. In the present 
case, the focal length of a single lens which 
would produce the same magnifying power 
would be one and a half inches. The propor- 
tion of the focal lengths of the two lenses to each 
other should be as three to one ; that is, if the 
field be one and a half inches, the eye-glass should 
be half an inch. An astronomical eye-piece 
may also be formed with two plano-convex 
glasses, placed with their convex sides towards 
each other, and at a very small distance from 
each other, namely, somewhat less than the 
focal distance of the lens next the eye. If, for 
example, one of the lenses were one inch focal 
length, and that next the eye three quarters of 
an inch, they might be placed at somewhat less 
than half an inch asunder. 

Diagonal eye-pieces. — ^When a celestial object 
is at a high altitude, the observer is obliged to 
put his head in a very inconvenient position, 
and to direct his eye nearly upwards, in which 
position a steady view of the object can scarcely 
be obtained. The diagonal eye-piece has been 
invented to remedy this inconvenience. This 
is eflfected by placing a flat piece of polished 

Fig. 14. 


speculum metal, d c, fig. 14, at an angle of 45^ 
to the axis of the tube, a b. This part slides 
into the tube of the telescope, e p ; the tube 
containing the lenses stands at right angles to 
the position of the telescope, and slides into an 
exterior tube, a n, i o, and the eye is applied 
at o. This construction of the diagonal eye- 
piece may be used either with the Huygenian 
eye-piece before described, or with that which 
is formed of two plano-convex lenses, with their 
convex sides towards each other. They may 
be of any magnifying powers generally applied 
to the. telescope, and may be changed at plea- 
sure. The rays proceeding from the object- 
glass and falling upon the plane speculum, d c, 
are reflected in a perpendicular direction to the 
eye-piece, e p, and enter the eye at g. When 
this eye-piece is directed to celestial objects at 
a high elevation, the observer may dtibec %»v\. <st 


stand, and ]ook down upon the object with per- 
fect ease. When it is directed to terrestrial 
objects, the spectator likewise looks down upon 
them, but they present a novel aspect, and 
when the telescope is moved from one side to 
another, they have the appearance of a moving 
panorama. When the eye-piece is turned round 
a quarter of a circle towards the right, those 
objects which are in the south will appear as if 
they were in the east ; when it is turned a quar- 
ter of a circle towards the left, they will appear 
as if they were in the west ; and when it is 
turned half round from its first position, they 
will appear as if they were above us, suspended 
in the air. 

A telescope furnished with a diagonal eye- 
piece is the piost convenient for exhibiting the 
spots in the sun. The window-shutters shoidd 
be all closed, having a small opening sufficient 
to admit the solar rajrs, and when the telescope 
is properly adjusted, a large and beautiful image 
of the sun, with all the spots which then happen 
to diversify its surface, is thrown upon the ceiling 
of the room, which must be of a white color 
In this way we may measure with a scale the di 
ameter of the solar image, and also the diametc 
of a large spot, and by comparison we may dete: 
mioe the exact diametrical proportion of the lattc 

Seoiios VI. — Refiectiiig telescopes. 

The great inconvenience attending tlie i 
. BgPraent of the long refracting telescope 
B smg!e object-glass, led to the invention of 
reflecting telescopes. It is generally supposed 
that Mr. James Gregory, son of the Rev. John 
Gregory, minister of Dmmouk, Aberdeenshire, 
■was the first who suggested the construction of 
that kind of reflecting telescope which bears 
his name ; but as he was eivAti^ni "frfla 



mechanical dexterity, he never actually formed a 
telescope according to his own theory. Several 
years after he had published his description of 
it, Sir Isaac Newton directed his attention to 
this subject, and, in the year 1672, completed 
two small reflecting telescopes, the construction 
of which somewhat differed from the plan 
Gregory had proposed in 1663. They were 
only six inches long, but were considered as 
equal in magnifying power to a common refract- 
ing telescope six feet in length. Nothing more 
was heard of reflecting telescopes till about half 
a century afterwards, when, in the year 1723, 
Mr. Hadley made a reflector on Newton's plan, 
the large speculum of which was sixty -two and 
five-eighths inches focal distance, and five inches 
diameter, and was furnished with magnifying 
powers of from one hundred and ninety to two 
hundred and thirty times. It equaled in its 
performance the telescope of Huygens, one hun- 
dred and twenty-three feet in length. Reflecting 
telescopes have been ever since in general use* 
and have entirely superseded the long refractan. 
We shall give a brief description of each of the 
telescopes to which we have alluded. 

1. The Newtonian reflector, — This instrument 
is represented in fig. 16, where b a b f is the 
tube, in which is placed the concave speculum 



B B, which reflects the parallel rays o c, f d, to 
a plane speculum q, which is placed at half a 
right angle to the axis of the tube, as much 
nearer the speculum than its focus as the centre 
of the small mirror is distant from the tube ; 
that is, the distance o A of the small speculum 
from the focus of the great one should be equal 
to o H, half the diameter of the tube. This 
small speculum should be of an oval form, the 
length of which should be to the breadth as 
seven to five. It is supported by an arm fixed to 
the side of the tube. The rays, o c,t d, which 

Pig. 16. 

B T ^^1 A 

form the image of the object by reflection, 
instead of proceeding to form it at h, are mter- 
cepted by the plane speculum at o, and reflected 
upwards to ^ aperture in the side of the tube 
A B, where the image is formed, and magnified 
by a convex lens of a short focal distance, to 
which the eye is applied, looking dotonward on 
the object, which appears inverted ; or, the eye- 
glass, iostead of being on the upper part of the 
tube, may be placed on one of the sides, and 
for viewing land objectft a t«XT^\xssi\ ^^^^\<^<:^ 


may be applied. Tbe magnifyiiig power o/" 
this telescope is in the proporlion of the fooal 
distance of the speculum to that of the eye-glass, 
Thus, if the focal length of the speculum be 
axty inches, and that of the eye-glass a quarter 
of an inch, the magnifying power will be two 
hundred and forty limes. This is the form oC 
the reflec^ng telescope which was moat gene- 
rally used by the late Sir W. Herauhel, Tim 
followmg table exhibits a statement of tixa dt 
ameters of tbe specula of Ifewtoiuan I'efleoton^ 
the focal distances of their eye-glasses, und thetr 
magnifying power: — - 


FactH diaUmm 


roCUl dlBlMM 






In. Dec. 

In. Deu. 



0.9U prl 
0.236 ' 













































It will generally be fouad, that the power pro- 
duced by muliiplying the diameter of the specu- 
lum by thirty or forty, is most satisfactory fu[ ■ 
planetary obserrations. J 

2. Tlis Oregorwn rejlector. — This form of th» 
reflecting telescope is constructed in the foUow- 
uig manner : — ^i' t t i is tie great tube, open at 
the end next the object, in which the lai'ge con- 
care speculum d u v f is placed, whose principal 
focus is at m, and in its middle is n round bole p, 
opposite to which is placed the small mirror l, 
concave towards Ihu great speculum, and so fixed 
on a strong wire m, that it may be moved farther 
from or nearer to the gi'etit miiTor. by means of 
a, long screw on the outside of the tube. Tlie 
rays proceedbg from the object a b, and falling 
on the speculum d f, will be reflected to its focus 
■m, where an inverted image of the object will 
be formed. 

This image is formed at a little more than ^ J 
focal distance of the small speculum from its sitf" I 
face, and the small mirror acting upon It, ttuftfl 
first image is reflected through the glass r to a ^m 
where a second image is formed erect, and lat; 
than the first in the proportion of 6 
This image is agwn magnified by the eye-glass s, 
to which the eye is applied. The rays from the 
glass s pass through the small hole « .'vVv^^on 

Idom be more tlian one twenty-fifth of an incli 
in diameter. To iind the magnifying power of 
this telescope, multiply the focal distanee of the 
great Epeculmn by t!ie distance of the small specu- 
lum from tlie image nest tlie eye ; and multiply 
the focal distance of the smalt speculum by tbe 
focal distance of the eye-glass ; then divide the 
product of the first multiplication by the product 
of the last, and the quotient will be the magni- 
fying power. 

3. Oaisagrainian reflector. — This kind of re- 
flector is constructed in the same wny as tbe 
Gregorian, with this difference, that a small eon- 
Vfx speculum is substituted in the room of the 
Email concave l, fig. lY. This convex mirror is 
placed as much leitkin tbe focus of the great 
speculum as is equal to its own focal distancft 
Thus, if the focal length of the large speoultsn 
be twenty-four inches, and that of the small coo- 
vex two and a half inches, they are placed >t 
twenty-one and a half inches fiom each other, 
and instead of two, there is ouly one image 
formed, namely, that in the focus of the eye-glass, 
The length of this telescope is leas than that of 
a Gregorian by twice the focal length of the 
small mirror. From the experiments of Short, 
Ramsden, Captain Eater, and others, it appeu> 
that there is more licrht in this t«le«coDe than h 






the Gregorian ; and that it is, on the whole, sn 
perior in its performance, but it represents ib 
object in an inverted position.* 

Short account of some large achromatic and n 

fleeting telescopes, 

1. Large achro7)iatic telescopes, — (1.) Tk 

great Cambridge telescope, in Massctchusetts 

United States, — ^This instrument was procurec 

from Munich, in Germany, at a vast expense, anc 

* Besides the telescopes described above, there an 
plans of others by which distant objects may be viewed 
1. A telescope may be made of a single lens of a lon| 
focal distance. The writer has a lens twenty-six feel 
focal distance and eleven and a half diameter, whicli, 
without any other glass, produces a magnifying powei 
of nearly thirty times, and by which he has read the 
hour of the day on a public clock two miles distani 
The observer stands at a distance of about twenty-fiTe 
feet from the lens, his eye serving as the eye-glass, 
on the principle of the Galilean telescope. 2. The 
aerial telescope, constructed by the writer, which has 
only one speculum, and in looking through which the 
observer sits with his back to the object. This teles- 
cope has no tube, but only a short socket to hold the 
speculum. An arm at one side extends the length of 
the focal distance of the speculum, at the end of whicb 
is the eye-piece. 3. The Newtonian telescope may alsc 
be fitted up toithotU a tubtj which saves considerate 
expense. The writer has fitted up one on this plan, 
which performs admirably. It may be changed at 
pleasure into the aerial teVe^cope. 


it is considered as one of the best instruments of 
the kind now in existence. The object-glass is 
fifteen inches in diameter, and its focal length 
twenty-three feet. It is placed on a block of 
granite, thirteen tons in weight, adapted to an 
equatorial apparatus, and clock-work is applied 
to it, to give it a quiet sidereal motion. Almost 
everything which has lately been discovered by 
Lord Rosse has been seen through this telescope. 
It has magnifying powers from two hundred and 
fifty to above one thousand times. (2.) Sir J. 
South*s telescope, — ^The object-glass of this tele- 
scope, which was procured at Paris, is eleven and 
two-tenths inches diameter, and nineteen inches 
focal length. Thb telescope is erected on an 
equatorial stand, at Sir J. South's observatory, 
Kensington. (3.) The Northumberland telescopCy 
in the observatory at Cambridge, is among the 
largest of the kind in Great Britain. The object- 
glass is said to be twenty-five feet focal distance, 
and of a corresponding diameter. (4.) Paris Ob- 
servatory . — In this observatory, when visited in 
1837, there were two large achromatic telescopes, 
which appeared to be jfrom fifteen to eighteen 
feet long, and the object-glass from twelve to 
fourteen inches diameter. (5.) The Dorpat teles- 
cope, — ^This telescope was made by Fraunhefer 
of Munich, for the observatory oi XW \\si^^^r^ 


Univereity of Dorpat, in the year 1825. Tbe 
aperture of the object-glass is nine and a half 
inches, and its focal length fourteen feet. lb 
magnifying powers range from (me hundred and 
seventy-five to seven hundred. It is moiinted on 
an equatorial stand, with clock-work, and it ooat 
£900. (6.) The Cincinnati telescope. — ^This tele- 
scope was procured from Germany, and fitted 
up by Professor Mitchell, of Cincinnati, United 
States. It is mounted on equatorial machinery, 
accompanied with clock-work. Its object-glass 
is nearly eighteen inches focal length, and twelve 
inches diameter, with magnifying powers from 
one hundred to one thousand four hundred times. 
The instrument with its machinery weighs about 
two thousand five hundred pounds. (7.) 2ir, 
Cooper' 8 telescope, — ^Mr. Cooper, M. P. for Sligo^ 
is in possession of a telescope, twenty-six fe^ 
long and the diameter of the object-glass is four- 
teen inches. (8.) Dr, Pearson's telescope. — This 
gentleman, who is secretary to the Astronomical 
Society, is in possession of a telescope made by 
the late Mr. Tulley, the object-glass of which is 
twelve feet focal length, and seven inches diameter. 
(9.) Mr, LawsorCs telescope, — ^This gentlemaOi 
who is a diligent astronomical observer, possesses 
a most beautiful telescope, twelve feet focal 
length, and seven inches diameter, made by one 

of the DoUoudB. It is said to bear poirerB of 
one thousand ane hundred or one thousand two 
hundred. (10-) Mi: SridrKs's telescope. — This 
\ gentleman has fitted up at Blackheath a. telescope 
I on equatoiiul machinety, whose object-glasa is 
I live and a. half feet focal Eength, and five and a 
I half inches diameter. The object-glass cost two 
hundred guineas, the equatorial machinery one 
" hundred and fifty, and the obsorvatory one hun- 
dred guineas ; in all, four hundred and fifty gui- 
" neas. (11.) Captain Sniilh'« telescope, at Bed- 
I ford. — This instrument is eight and a half feet 
I fo<ml leagtli, and sh inches diameter, and will 
bear a maguifying power of one thousand two 

2. Larye mjlectini/ lelfKopea. — Mr. Jaraes 
' Short, of Edinburgh, was the first who made 
I reflecting telescopes on a large scale. In 1743, 
he constructed one for Lord Spencer, of twelve 
' feet focal length, for which he received six hun- 
dred guineas; and, in 1752, bo finished a still 
larger one for the King of Spain, for which he 
received one thousand two hundred pounds 
Bterling, This was considered the noblest in- 
Btrument of its kind till Herschel constructed 
his large reflectors. About the year IVSO, the 
late Sir W. Ilerschel constructed a Newtoniaji | 
. reflector, twenty feet long, with which he « 



plored the Milky Way, and other objects in the 
sidereal heavens. In 1789, he finished his large 
forty-feet telescope, which at that time was un- 
rivaled. Its speculum was four feet diameter, 
and it had neither a concave nor plane small 
spectdum, but the observer sat with his back to 
the object, and looked down upon the great 
speculum. This telescope was dismantled a few 
years ago. A large telescope, twenty feet in 
length, has lately been constructed by Mr. Lar- 
sels, of Liverpool, with which he has discovered 
several small planets. But the largest reflectorB 
now in existence are those which have been 
lately erected by the Earl of Rosse. One of I 
these, in the lawn before his lordship's mansion^ 
is twenty-seven feet long, and its speculum three 
feet diameter. Another, called the ''monster 
telescope," is fifty-six feet long, and its speculnm 
six feet in diameter, and weighs above three 
tons. This is the largest telescope in the world, 
and its erection cost his lordship twelve thou- 
sand pounds sterling. It is of the Newtonian 

Prices of telescopes, of a moderate size, as made 
by the London opticians, — ^To such of our readers 
as may be desirous of puirsuing astronomical 
studies, the following list may be useful. 

The instruments specified in the preceding 


pages are only made lo order, nnd are, conse- 
qoently, very expensive. The more common 
sjzea of telescopes for astronomical purposes are 
the following ; — 

1. Achromatic lelescopes. — '' The improved 
tno and a half feet achromatic, on a brass stand, 
msliogaoy tube, with three eye-pieces, two mag- 
nifying about forty or fifty Umes, and the other 
about seventy-five for asLrooomical purposes, in 
malu^^any case, illO 10s. ; ditto, with brass tube, 
illl lis.; ditto, vith vertical and horizontal 
rackwork motions, £I5 15«." This telescope, 
if the objeot-glasa be good, will bear a power 
of ninety or one hundred times for oeleatial ob- 
jects. Its ohjecL-gluas is two and a quarter 
inches diameter. " The three and ii half feet 
uchromalic, plain mahogany tube, two and three- 
qujirters aperture, £18 ie». ; ditto, brass tube, 
• £21 ; ditto, all in brass, with nickwork motions, 
£26 &j. ; ditto, the object-glass of throe and a 
quarter inches aperture, and having improved 
rackwork motions, from £37 Ifls, to £42." The 
magnifying powers of these telescopes are from one 
hundred and thirty to one hundred and eighty or 
two hundred times. Tliis is the telescope whiA. 
we would recommend to iistrouomical observeiK.] 
It will show all the common phenomena o 
solar system, Tho fire ftti tttitTomi).ti.t '\ 


frequently made: diameter of the object-giB» 
three aad eight-tenths inches ; powers, sixty-fiv6i 
one hundred and ten, one hundred and ninety, 
and two hundred and fifty. Its general price is 
above one hundred guineas. Achromatic object- 
glasses for such teSescopes may sometimes be 
purcliased separately, at such prices as the fol- 
lowing ; — Focal length, thirty inches, diameter 
two and a quarter inches, from two to two and 
a haJf guineas ; focus forty-two inches, diameter 
two and three-quarter inches, from five to eight 
guineas ; focal length forty-two inches, tUameter 
three and a quai-Ler inches, from twelve to twenty 
guineas. Eye- pieces may be procured from 10». 
erf. to 14)1. 

2, Rejieclini/ telescopes. — The reflectors oom- 
mouly made and sold in London are the follow- 

A four feet seven inch aperture, Gregorian- 
reflector, with the vertical motions upon a new 
principle, with apparatus to render the tube 
more steady for observation, according to the 
additional apparatus of small specula, eye-piecea, 
micrometers, etc., from £S0 to £120: three feet 
long, mounted on a brass stand, £23 3s. ; ditto, 
with rackwork motions, improved mountings aad 
metals, £30 16«. ; two feet long, without rack- 
Work, and with four magnifying powers, Xld 

!ce tt/^^M 

16s.; ditto, improved, irith raokwork motioi^ 
£22 1«, ; eighteen inch, on a. plain stand, £0 9s, ; 
twelve inch ditto, £8 6j. 

Sectios TII, — Discoveries which have been 
bi/ meam of ike telescope. 
The human eye is a most wonderful piece 
mechanism; it is a natural telescope, nearly 
spherical in its form, and exquisitely delicate 
and beautiful in its struoturc. The complete- 
ness of its organization, and the perfect ease 
and rapidity with which it fulfills all its functions, 
show that He by whom it was " formed " de- 
signed it to minister continually to our instruc- 
tion and happiness. We need not endeavor to 
imagine what would have been our helpless and 
hopeless state oL uncertMnty, confusion and dis- 
tress, had we been without tho faculty of sight. 
Almighty wisdom and benevolence could not 
f(ul to render our existence harmonious, to adapt 
our perceptions to our condition, and to endow 
us with those senses which are necessary to a 
wise and satisfactory enjoyment of life. " Of 
all our senses," says Mr, Addison, "our sight is 
tlie most perfect and delightful ; it fills the mind 
with the largest variety of ideas, converses with 
its objects at iho greatest distance, and coatini 
the longest, in action without b«,\'C;^ ^n«t&. 


satiated with its proper enjoyments." Abon 
all is it Tallied by those who, in the oo namloi 
ness of their relati(»i to God as bd&even k 
Christ, rejoice to commune with hinoi m the 
works of creation. '*The endless Tolttme of 
nature, full of beauty, and illuminated by Hea- 
ven, seems to them sufficient to fill the soul with 
satisfaction forever, because here they leam k^ 
miliarity with the attributes of a Power Hmj 
may trust as thoroughly as they can admiiB.***^ 
But our vision, at the best, is feeble, and H ii 
limited within a very narrow range. From Iks 
brow of a hill we may look on an ex tcu M Ue 
landscape, but it is only within two or tkne 
miles that its varied beauties are distinctly seea 
Even at this distance we cannot distingiiish a 
friend, or read a sign, or accurately desoribeHiB 
actions of our fellow-men. If we gaze up into 
the sky on a dear evening, we see the. moon, it 
may be a slender crescent, or a full enlightened 
orb, or one of the vfflied phases between ihittlte 
two extremes ; we see five or six hundred glelnift- 
ing sparkles of light, which we call stars, 
we see a lustrous cloud eneompasring a 
siderable part of the heavens : but here the dk- 
coveries of unassisted vision terminate. 8oiift 

o The Influence of the Body in relation to the MbtiK 
Bjr George MooKt M.D. 



more intelligent and scrutinizing inquirer may, 
indeed, detect differences which others overlook, 
and perceive order where they only find confu- 
sion; and these observations may suggest to 
him truer and sublimer conceptions of the uni- 
verse than the unassisted organs of vision can 
give. But he can be satisfied with nothing less 
than cei-tainty, and he is bewildered and op- 
pressed by doubt and mystery. To him how 
valuable are the discoveries of the telescope, 
and how important are they to all, for the stu- 
pendous proofs which they afford of the omnipo- 
tence of the Creator, and of the vastness of his 
dominions ! 

We shall now give a brief sketch of these dis- 
coveries, both within the solar system and in the 
sidereal heavens. 

Discoveries in the solar system. 

The moan, — The nearest to the earth of the 
heavenly bodies is the moon. By the telescope 
it has been discovered that a very large number 
of mountains diversify its surface. They are 
from half a mile to ^yq miles in perpendicular 
elevation, and are almost universally rounded in 
their form. They may be classed in the follow- 
ing order: — 1. liisulaied mountains which rise 
from plains nearly level, like Ok ^^Oii^Asi^ ^^Ri^^ 


table. 2. Ranges of mountains, extending in 
length three or four hundred miles, resembling 
our Alps and Apennines. 3. Circular ranges, 
surroimding either a cavity or an extensive plain, 
from which rises centmlly a mountain of con- 
siderable height. There are also caverns in the 
moon, some of which are more than two miles 
in perpendicular depth. Their diameter varies 
from three to forty or fifty miles, and the larger 
ones have flat bottoms. Nearly a hundred of 
these caverns may be seen on the south-western 
part of the planet. Although there are large 
regions in the moon perfectly level, and which 
seem to be of an alluvial character, no seas or 
large collections of waters can be discerned in 
it, and in its atmosphere there is no appear- 
ance of clouds. It has been ascertained that 
the moon always turns the same side to the 
earth, so that we see nothing of the other hemis- 

The Sun, — Among the first discoveries of the 
telescope was the motion of certain dark spots 
across the disc of the sun. T^ey have since 
been more closely observed, and by them it has 
been calculated that the sun revolves on its axis 
in twenty-five days and ten hours. These spots 
are of various sizes, from one twentieth of the 
8UD*8 diameter to one five hutvdxedtVv oxvii \v\der. 



Tliey have a dai-k centre, surrounded hy a bor- 
der of fainter shade, called an umbra. Some- 
times the sBme umbra includes one or two large 
spots and a, number of very small < 
other times the latter accompany the former H 
n kind of train. Occasionally the s 
i\lraoat free from spots, but often nearly a hnw 1 
dred may be seen on its surface at one time. 
The sun ia supposed to lie a solid globe, sur- 
rounded by a luminous atmosphere, from whence _ 
heat and ligW are diffused through the p!aM 
tary system, it is probfthle the f 
opnque hody seen through that atmosphei' 
■when any portions of it more rare or thinni 
tban usual. 

Vemis and Mercary. — Venus is the brightd 
of the planets, and is known as the morning a' 
the evenbg star : it is the morning star when it 
is west of the sun. and rbes before it; and the 
eTemng star when it is east of the sun, and setfr^g 
after it, One of the earliest discoveries of t 
telescope was the fact that Yenus passes thro 
the Barac phases as the moon, appearing, ; 
its inferior conjunction with the sun, and when 
its dark side ia turned towards the earth, first 
as a crescent, then as a half moon, then gibbous, 
and at length a.s a full enlightened hemispher^j 
This discovery was an impottiiiA ccfl&TvwS.vaa."?r 



, sur- 

hen it 
d the 
md setfr'^^_ 

g, afta^H 

tlie theory of Copernicus, tliat this planet did 
not move round the earth, as was formeHj 
supposed, but round tlie sun, and in an ortit 
between the earth and the sun. It proved, also, 
that the planete are dark bodies, and derive flU 
their light from the centi'al luminary. From 
subsequent elimination it was found that yenns 
turns round its axis in twentj-thrce hours and 
twenty-one minutes. With the telescope it baa 
been observed on different occasions to transit 
the sun's disc, by which the distance of the sun 
has been more accurately detennined. Pew 
discoveries have been made in Mercury, on ac- 
count of its nearness to the sun. It has been 
found, however, that it passes through all tbo 
phases of the moon, in the same way as Venus; 
tliat it moves round its axis in twenty-four hotm 
and three minutes ; and that high elevations pro- 
ject from its surface. 

Mam. — ^This planet is remarkable for its 
color, which is a glowing red. Sometimes it 
looks nearly as lai^ as Jupiter, and at other 
times it appears as if it had dwmdied lo the Nze 
of a small star. These variations are owing U> 
its different distances from the earth, the two 
extremes of which are fifty, and two hundred 
and forty millions of miles. It moves in an orbit 
e distant from the sun than that of the earth. 

and accomplishes its revolution In one yeav and 
ten months. Spots have been diecove/^ed on ils 
aurfuce, whicii seem to indicate the existence of 
land and water. A wliit<i spot has likewise 
been discovered near its south pole, which is 
supposed by some to ariee from the reflection 
of the sun's light around the polar region^ 
The red hue of Mars is occasioned by the dei 
atmoephere with which ]t is surrounded. 
watching its spots it has been found to have 
rotation round its axis in twenty-four hours and 
thirty-seven minutes. This planet is of a Bphe- 
rcudal figure, like the earth, having its polar 
diameter two hundred and sixty-three miles 
shorter than its equatorial, which is four thou- 
sand two hundi-ed miles. From these and 
other obsen-Jitions, it has been concluded that 
about one-third or one-fourth of its surface is 
covered with water, that there ate strata of 
clouds of con^derable extent occasionally float- 
ing in its atmosphere, and that it has 
of seasons similar lo our own. 

TTie nrai planets between the orbits of 
and Jupiter, — Within the Umilti of the present 
century, certain comparatively small anomalous 
bodies have been discovered, revolving around 
the sun in the re^ons between the orbits 
Uars and Jupiter, The great dlatance 



' float- 


inteirenes between Mars and Jupiter led astro- 
nomers to suppose that a planet existed some- 
where witbih that part of the planetary system. 
But they were astonished when it was fonnd 
that not only one planet, but a considerable 
number, were running their courses m that 
region. The first of these planets was discover- 
ed on January 1st, 1801, by Piazzi, at Palermo, 
which is named Ceres; the second, named •Tuno, 
by Professor Harding of Gottingen, in 1804; 
the third and fourth, named Pallas and Vesta, 
in 1802 and 1807, by Dr. Olbers of Bremen. 
No further discoveries were made till December 
8th, 1845, when Professor Hencke of Driessen 
discovered Astroea ; and on the 6th July, 1847, 
the same gentleman discovered the planet JSSpftf. 
Mr. Hind, at the Observatory, Regent's Fait, 
London, August 18th, 1847, discovered Iris, and 
on the 18th of October, the planet Flora, On 
April 25th, 1848, Mr Graham discovered Metis, 
On the 12th April, 1849, M. De Gasparis, of 
the Observatory at Naples, discovered Hygeia; 
and on the 11th May, 1850, another, which he 
calls Parthenope. On September 13thy 1850, 
Mr. Hind discovered another planet in the con- 
stellation Pegasus, which appeared like a star of 
the ninth magnitude, and with a pale bluish 
Ji^ht; he intends to call it Victoria, This fomns 


the twelfth of the group of the new planets, of 
which eight have been discovered within the 
space of little more than four and a half years. 
All these planets are invisible to the naked eye, 
and<2onsequently their existence would never have 
been known without the telescope. Their mag- 
nitudes are not yet accurately decided. Shroeter, 
a celebrated Oerman astronomer, calculated the 
diameter of Vesta at two hundred and seventy- 
six miles, of Juno at fourteen hundred and twenty- 
five miles, of Ceres at sixteen hundred and twenty- 
four miles, and of Pallas at about two thousand 
miles. There is a considerable degree of mys- 
tery connected with these planets, which it is 
not easy to unravel. Their orbits have a much 
greater degree of inclination to the ecliptic than 
those ci the other planets ; they are more ec- 
centric, and several of them cross each other ; 
they revolve nearly at the same distances from 
the sun, they perform their revolutions nearly in 
the same periods, and they are all much smaller 
than those previously discovered. It has been 
thought, therefore, by some, that these planets 
are the fragments of a greater planet, which had 
fcnrmerly circulated between Mars and Jupiter, 
and which an hnmense irruptive force from its 
interior had burst asunder. This, however, is 
mere speculation. 



68 THE TELB800FK. 

Jupiter, — This is the largest planet in i 
solar system. It is eighty-eight thousand mi 
in diameter, and in bulk exceeds that of t 
earth about thirteen hundred times. Dark beL 
which frequently shift their position, and vf 
in breadth as well as in situation, embrace 
whole circumference. These belts are, probab 
it« real surface, and the intervals between tb 
some astronomers suppose to be the clouds in 
atmosphere. Large spots have been seen 
Jupiter, and by these it has been shown that 
revolves round its axis in nine hours and fift 
six minutes. It is attended by four moons, 
satelUtes, which, it will be remembered,. w( 
among the first discoveries made by Galileo wi 
the telescope. These satellites are seen indiffi 
ent positions. Sometimes two are seen on o 
side of their primary, and two on the other sid 
and sometimes all four are seen in their regul 
distances on one side, nearly in a straight li 
from each other and from the centre of i 
planet. At other times, only two are visib. 
the other two being eclipsed by the shadow i 
Jupiter. The first satellite, or that nearest tl 
planet, revolves round it in forty-two hours ai 
a half, and suffers an eclipse eighteen times 
every month. The eclipses of these satellit 
are of considerable use in determining the lon^ 


tude of places on tbe earth. Jupiter, with his 
moons, which are all invisible to the naked eye, 
is a most splendid object when seen through a 
powerful telescope, and presents a field for con- 
templation which never fails to astonish and 
delight by its magnificence and variety. 

Saturn, — The planet Saturn is nine hundred 
and six millions of miles from the sun, which 
is nearly double the distance of Jupiter. It is 
seventy-nine thousand miles in diameter, and 
nearly a thousand times larger than the earth. 
It has dght satellites. Some dusky spots have 
been occasionally seen on its surface, by the 
motion of which its diiunal rotation has been 
found to be accomplished in ten hours and six- 
teen minutes. Belts have likewise been discov- 
ered in Saturn, almost resembling those of Jupiter, 
but fainter, and invariable in their position. 
The belts of Saturn also cover a larger zone on 
the disc of the planet. But the most remark- 
able discovery which the telescope has made in 
connection with Saturn is, that, at a distance from 
it of more than twenty thousand miles, it is sur- 
rounded by an immense double ring. This ring, 
or rather these rings, are concentric with the 
planet and with one another, both lying in 
one plane, and separated from each other by an 
interval of more than two tho^isoxvixfiaiSL^^. ^^^^ 


'Utside diameter of the exterior ring exceeds two 
lundred thousand miles, its circumference is up- 
wards of six hundred and thirty thousand miles, 
and its breadth is seven thousand two hundred 
miles. The outside diameter of the interior ring 
is one hundred and eighty-four thousand miles, 
and its breadth twenty thousand miles. These 
rings, reckoning the extent of surface on both 
sides, contain an area of more than twenty-eight 
thousand eight hundred millions of square miles ; 
that is, it is equal to one hundred and forty-sax 
times the number of square miles on our own 
terraqueous globe. The rings revolve round the 
planet every ten hours and a half, which is at 
the rate of more than a thousand miles every 
minute. They preserve an invariable distance 
from the planet at all times, and along with it 
are carried round the sun in the space of twenty- 
nine years and a half. If viewed from the planet 
itself, they would appear like magnificent lumi- 
nous arches, stretching from east to west across 
the heavens, and difiPusing at night a mild radi 
ance. From our distant point of observatioi 
we may learn by these stupendous phenomei 
that Omnipotence is everywhere present, a' 
that He who regulates and keeps in perfect h 
mony the movements of all worlds, must be 
in£mte m goodness as he k in ^ower. 


Uranus. — ^This planet is 1,800,000,000 of 
miles from the sun, and about 900,000,000 of 
miles beyond the orbit of Saturn. It remained 
invisible till the year lYSl, when the telescope 
revealed it to Sir. W. Herschel. It revolves 
round the sun in an orbit 11,314,000,000 of 
miles in circimiference, in the course of about 
dighty-four years, at the rate of fifteen thousand 
miles an hour. Owing to its great distance from 
uSy. no spots or belts are discernible on its sur- 
face, and consequently the period of its diurnal 
rotation is unknown. Its magnitude is estimated 
at thirty-five thousand miles in diameter, or 
about dghty-two times larger than the earth. 
It has four satellites, and probably five or six ; 
but their periods are not ascertained with ac- 
curacy, and their orbits present remarkable 

NeptwM. — ^This planet was discovered on the 
28d of September, 1846, by Dr. Galle, of the 
Royal Observatory at Berlin. Its place had 
been calculated, even before it was discovered, 
by Mr. Adams of Cambridge, and M. Leverrier 
of Paris, by whom its position in the heavens 
was pointed out within a degree of the spot 
where it was actually found. It is probably the 
planet whose existence and position had been 
also calculated by Professor Challis of the Ob- 


servatory of Cambridge, on the 4tli and the 12tik 
of August, 1846, but he declined publishing fail 
observations at that time. Neptune appears Hke 
a star of the eighth magnitude ; its distance 
from the sun is about thirty times that of the 
earth, or more than 1,000,000,000 of nules be- 
yond the orbit of Uranus. Its diameter is fifty 
thousand miles ; it is therefore two hundred and 
fifty times larger than the earth, and its revolu- 
tion round the sun is accomplished in one hun- 
dred and sixty-four years. Mr. Larsels of 
Liverpool, from several observations has con- 
cluded that it is surrounded hy a ring, and Pro- 
fessor Challis and others have formed the same 
conclusion. Mr. Larsels has also ascertuned 
that it has two satellites, one of which revolves 
round it in five days twenty hours and fifty 

Discoveries made hy the telescope in the sidereal 


Of late years the telescope has been more 
particularly directed to the starry heavens than 
in former times, and many wonderful discoveries 
have been made, of which it is impossible to give 
more than a meagre outline. 

1. The distance and magnitude of the fixed 
stars, — ^The determination of the distance of 8 

ttar depends on the angle of paralkjt formed by 
viewing it from opposite parts of the earth's 
Jttbit, which ^ves a base line of 190,000,000 of 
niles in eitent. But the angle formed by thia 

fine at the stars is so small, that astronomers ' 

jfaave had great difficulties to encounter in order I 
io adjust it. Of late, however, this point has 
Jbeeti settled in reference to some of the fixed 
Mbtb. Professor Bessel, some years ago, deter- 
painedthe angle of parallax of the star sixty-one 

Ct/ffni to be somewhat more than one-third of a . 

)|scond, 'which makes the distance of that star to 1 

^ above aixti/ billions four hundred thousand 1 

pKilliora of miles, a distance through which light, J 

^yiDg at a rate of one hundred and ninety-two 1 

Ihousand miles every moment, would require tou' I 

ifears to pass. Another star, a Cenlouri, has ■ 

JtliA its parallax determined to be the ten- 1 

jtlevenths of a second, which mokes the distance 1 

||Ah>70 twenlij billions of miles. And as the ] 

bttSgnitude of a. st«r depends upon our knowing j 

pta distance, the magnitude of these stars must J 

•be mncl) larger than that of our sun. J 

j The Milky Wny.^'Ous is an irregular white ] 

^ono, which, with some variations, eocompassea J 

,tite heavens in a great circle, inclbed at an ■ 

:lBgle of 03° to the eqiunoctial. The telescope 1 
AaB enabled us to ascertain thtri. l\i« -«\iAjn«aft 1 



of this zone is owing to the countless multitude 
of stars which it contains. In a powerful ghm, 
the field of view will be filled with more than a 
hundred stars; and turning the instrument to 
the right and left, or up and down for a con- 
siderable distance, a similar niunber will appear 
with every change of its position. So crowded 
are the stars in some parts of this zone, that Sir 
W. Herschel, by counting the number in a single 
field of his telescope, concluded that fifty thou- 
sand had passed under his review during an 
hour's observation. It has been calculated that 
in the Milky Way there cannot be less than 
twenty tiiillions of stars, which is twenty thou- 
sand times the number of those visible to the 
unassisted eye. And if every star be a splmidid 
sun, surrounded with planets, as we have every 
reason to believe, how overpowering is the sense 
of indefiniteness as to the extent of the universe I 
And yet when we see ** confused clouds of gloiy 
revolving themselves into systems of orderly 
worlds," we rejoice in the thought, that He who 
made them ** telleth the number of the stars ; 
he calleth them all by their names," Psa. cxlvH, 4; 
and that with him order and arrangement indi- 
cate a ceaseless and beneficent superintendenoe 
of all '* the works of his hands." 
Double 8tar8.-^T\ie;re axe numbers of stan in 


the heavens, which appear single to the naked 
eye, but when viewed through a telescope are 
discovered to be double, and sometimes triple, or 
quadruple. These double stars are generally of 
different magnitudes ; and it has been frequently 
found, after a long series of observations, that 
the smaller star performs a revolution around 
the larger one. Above fifty instances have 
been ascertained in which one star revolves 
round another; and although insome of -these a 
complete revolution has not yet been witnessed, 
yet from what has been observed, the period of 
entire rotation has been determined. One of 
these stars, ri Coronse, accomplishes its revolu- 
tion in forty-three years ; another, a Leonis, 
in eighty-two years ; and another, a Castor, in 
two hundred and fifty-two years. Here we have 
the astonishing spectacle of suns revolving around 
BunSy and systems around systems! Another 
interesting fact is, that these stars frequently 
exhibit contrasted colors : the large star is usually 
of an orange hue, while the smaller one appears 
Uue or green ; in other cases, the large one is a 
white star, and the smaller one a rich ruddy 
purple. What a dissimilar illummation must these 
suns afford, yet how beautifully do their colors 
harmonize ! The works of God are as perfect as 
they are inexhaustible in wonders QiSid\TiNm<^\?j . 


not more than a tenth part of that covered hf 
the moon." More than three thousand nebuls 
have been discovered in different parts of the 
heavens ; and if they are all resolvable into as 
many stars as this calculation supposes, it wOl 
add fifteen millions to the number before be- 
lieved to exist. But some of the distant nebulse 
are thought to equal the Milky Way in the 
number of stars; for if that galaxy had been 
placed at such a remote distance from ns as 
some of the nebulee, it would have appeared 
no larger than these now do, when beheld as 
dim specks even through the telescope. The 
planetary nehulcB are a very extraordinary ckss 
of objects ; they have a near resemblance to 
planets, presenting discs round or slightly ovaL 
One of these is situated somewhat south of the 
parallel of j3 Wrsce Majoris, and about 12' follow- 
ing that star. Its apparent diameter is 2^ 40" ; 
and " supposing it placed," says Sir J. Herachd, 
'* at a distance no greater than that of sizty-<Hie 
Cygni, would imply a linear diameter seven 
times greater than that of the orbit of Neptune." 
Now, a body seven times the diameter of the 
orbit of Neptune would be nearly twenty thou- 
sand millions of miles in diameter. Of such a 
body we can have no adequate conception. We 
are overwhelmed by its magnitude, and can 


The cause of their variation is unknown, thougii, 
ia Bome instances, there can be little doubt that 
it is occaaioued by the interposition of opaque 
bodies, snch as the planets, 

Clwters of stars and the Nebulis. — When 
we look up to the heavens in a clear evenmg, 
we perceive groups of stars compressed within 
narrower limits than other constellations. Then 
is a remarkable chieter, called the Pleiades, ia- 
which a common telescope shows about sixlf 
largo stars crowded together. There is anothOTi. 
scarcely visible to the naked eye, in the con* 
Btellittioa Cancer, called Prasept, which contain* 
about forty or lifty brilUanl stars ; and in thd 
Bword handle of Perseus there is a most beau- 
tiful group, which can only be seen with a tele- 
scope. They are called clusters, and are sup- 
posed lo be drawn together by the influence of 
cert^n physical laws. Jf^ebulw is the name 
given to small cloudy spots which are seen in 
the heavens. Many of these nebulse are found 
to be thick set with stars, which powerful tele- 
scopes alone enable ua to distinguish. They 
are not to he reckoned by hundreds, but hf 
thousands. "On a rough calculation," saya. 
Sir 3. Herschel. " it would appear that maay 
clusters of this description must contain at least: 
five thousand stars, compacted in a round sftaot 




Beflections suggested hy the discoveries of (A 


1. How impressively do the discoyeries of th 
telescope illustrate the ahnighty power of God 
Let the reader reflect for a moment upon th 
view which this admirable instrument presenl 
of the extent of creation. There was a tinM 
when the conception of neither poet, philosophe 
nor divine, soared beyond the sphere of iinaide 
human vision ; and when, looking upon the eart 
as the lai'gest body in the universe, and tl 
sim, moon, and stars as mere appendages 1 
enlighten and adorn it, they imagined all tli 
Creator's works to be confined within thee 
narVow bounds. But the telescope ha& opene 
to us a field to which no limits can be assignei 
Within our own planetary system it has dii 
covered to us bodies more than a thousan 
times larger than the globe we inhabit ; and i 
the distant starry regions, beyond our nean 
circle, it has shown to us myriads oi sun 
equal in magnitude to the one which rules oi 
day, and each the centre of other worlds* a 
of which are probably teeming with happ 
dwellers. Nor is this all; for as one bi^ 
scene of splendor rises above another, in alma 
boundless perspective, who can doubt that other 


yet more wonderful and Bublime, lie beyond the 
range of the most powerful telescope? ^ 
it lias taken us to the farthest line of ohs 
tion it can reach, who will say that " the 
iere of the Almighty are at an end, because ne 
fflR no longer trace his footeteps ? — that his 
iupotence is ezliausted, because human heart' 
can no longer follow him ?" 

Scarcely less calodsted to raise onr concept 
lionB of the almighty power of God, is the maff- 
Hilitde of the objects whiclk the telescope brings 
under our notice. The planet Jupitci 
puted to be more than thirteen hundred limes 
larger than the earth. The sun is five hundred 
times larger than all the planets and comets 
would be, were it passible to unite them 
TBst globe. The star a Lyric is reckoned to be 
three million two hundred and sevenly-five thi 
sand mile* m diameter, and more than fifty-four 
thousand times larger than the sun. Omnipo- 
tence is impUed in the existence of an atom as 
well as of a world, but we realize that atlribut*' 
mora vividly in the latter than b the former. 
We look at our own globe, with all its mighty 
oceans and contment«, conttuaing more than two 
hundred and sixty thousand millions of cubical 
miles of solid matter, and -we are astonished at 
the power of the Creator ; but bow ^ tiiSS. 





tonisbment increased, when ve leam from the 
discoveries of the telescope, that, instead of be- 
ing disHnguislied from otiier worlds, it ia one of 
the least of them — a mere atom in creation ; and 
(hat in coinparison nith other systems, the ons 
in which this atom is fomtd is but a mere shred, 
which, though scattered into nothing, wDnM 
leave the universe of God one entire soeno d 
greatness and of majesty 1 

To these considei-ations may be added the 
veloetty with which these stupendous bodies more 
in their courses. The planet Saturn, with Its 
rings and moons, moves in its circuit round the 
stm at the rate of twenty-two thousand roilee an 
hour, The planet Venus performs its revoliition 
ttt the rat* of eighty thousand miles an hour, 
and the planet Mercury flies through its orUt at 
the extraordinaiy speed of one hundred and nine 
thousand miles an hour. The motion of some 
of the fixed stars, a million times larger than the 
em-th, has been calculated to he one hundred 
and seventy thousand miles nn hour, and the 
velocity of some of the comets is known to be 
no less than eight hundred thousand miles an 
hour, or more than thirteen thousand miles p 
minute. When we reflect, too. on tlie size am 
number of the heavenly bodies, on the proba 
lii/U}' that they all move with a tftplM'j ■« 


if it be not impossible to calculate, is most diffi- 
cult to conceive, and that there is an order and 
harmony in their motions which prove them to 
be controlled and regulated by a will as omnipo- 
tent as that which called them into existence, we 
cannot refrain from exclaiming with the psalmist, 
when he thought upon the glories of the firma- 
ment, " Great is our Lord, and of great power." 
Psa. cxlvii, 5. 

2. How striking and beautiful is the coinci- 
dence between these discoveries of the telescope 
and the representations of Scnpture ! It is im- 
possible to determine whether the wonders which 
modem astronomy has brought to light were re- 
vealed to the sacred writers. But how remark- 
ably consistent is their language with all the 
wonders which the telescope has revealed ! 
Where would the devout astronomer, laying 
down the instrument with which he has explored 
the heavens, find the most suitable expression 
for those feelings which have been awakened by 
what he has there seen of the glory and power 
of the eternal Creator ? Where would he find 
language more elevated and appropriate than in 
the sacred volume? And in this concurrence 
between science and Scripture, have we not an 
additional confirmation of the fact, that the God 
of nature is the God of the Bible ? 


3. All subjects, as they are exhibited i 
Bible, have reference to the great work < 
demption. The cross of Christ is a centre 
whence the Christian will survey the uni 
The hill of Calvary will be his observatory 
how unutterable will be the emotions with 
he will " consider " the heavens, when he re 
bers that their almighty Maker is his Rede< 
"All things were made by him; and wi 
him was not anything made that was m 
John i, 3. There is a rapture felt in gazv 
the starry sky, which can be only known t 
in whose heart the Saviour is enthroned. 
will see all the glories of creation reflect! 
the mediatorial work of that Saviour, and 
discovery which expands his views of the f< 
will exalt his conceptions of the latter. " [ 
worlds of light," he will say, " those cou 
suns and systems which the telescope I 
within my sight, and in the contemplatic 
which, either individually or collectively, 
lost in astonishment and filled with awe, a 
the workmanship of my Redeemer. And 
so ? Then how transcendant must be his g 
Do I go to Bethlehem, the place of his inc 
tion, and see him, 

* On whom the vast universe hung,' 


as an infant cradled in a manger? What an 
infinite depth of condescension ! Do I visit the 
place of his crucifixion, and see him bearing 
' our sins in his own body on the tree V 1 Pet. 
ii, 24. How inestimable mu§t be the value of 
the sacrifice ! Does my faith follow him from 
the scene of his abasement to that of his exalta- 
tion? Do I behold him as Mediator, invested 
with absolute and unlimited sovereignty ? How 
is my confidence strengthened ! Surely * he is 
able also to save them to the uttermost that 
come unto God by him.* Heb. vii, 25." . 

Nor let it be imagined that the magnitude of 
cregtion affords any reasonable objection to the 
scheme of redemption as revealed in the Bible. 
The objection has been made ; but its whole force 
is met in the one simple consideration, "that 
God, in addition to the bare faculty of dwelling 
on a multiplicity of objeOT at one and the same 
time, has this faculty in such wonderful perfec- 
tion, that he can attend as fully, and provide as 
richly, and manifest all his attributes as illus- 
triously on every one of these objects, as if the 
rest had no existence, and no place whatever in 
his government or in his thoughts."* And in 

^ " Discourses on the Christian Revelation, viewed 
in connection with modem Astronomy," by Rev. Dr. 


illustration and proof of this position, let it be 
remembered that soon after the invention of the 
telescope, which put infidelity in possession of 
the objection, another instrument was found, 
** which laid open a scene no less wonderful, and 
rewarded the inquisitive spirit of man with a dis- 
covery which serves to neutralize the whole of 
this argument. This was the microscope. The 
one/' said that great man whose language we 
quote, " led me to see a system in every star. 
The other leads me to see a world in every atom. 
The one taught me that this mighty globe, with 
the whole burden of its people and of its coun- 
tries, is but a grain of sand on the high field of 
immensity. The other teaches me that every 
grain of sand may harbor within it the tribes 
and the families of a busy population. The one 
told me of the insignificance of the world I tread 
upon. The other refwsms it from all its insig- 
nificance ; for it tells me that in the leaves <rf 
every forest, and in the flowers of every garden, 
and in the waters of every rivulet, there are 
worlds teeming with life, and numberless as are 
the glories of the firmament. The one has sug- 
gested to me, that beyond and above all that is 
visible to man, there may lie fields of creation 
which sweep immeasurably along, and caiTy the 
Impress of the Alnngbty's Taood \^ t\i<^ xemotest 

scenes of the universe. The other suggests 
me, that within and beneath all that minutenesa 
-which the aided eje of man has been able to 
explore, there may lie a region of invisibles ; and 
that, could we draw aside the inysterions curtain 
which shrouds it from ouc senses, we raight there 
see a theatre of as many wonders as astronomy 
has unfolded — a universe within the compass of 
B point GO small as to elude nil the powers of 
the microscope, but where the wonder-working 
Gnd finds room for the exercise of all liis attii- 
butes, where he can raise another mechanism of 
worlds, and fill aud animate them all with the 
evidences of hia glory. 

" Now mark how all this may be made to 
meet the argument of our infidel astronomera. 
By the telescope they hiwe discovered that no 
magmtude, however vast, is beyond the grasp of 
the Divinity, But by the microscope we have 
also discovered, that no minuteness, however 
slirunk from the notiee of human eye, is beneath 
the condescension of his regard. Every addi- 
tion to the powerB of the one instrument, ex- 
tends the limit of hia visible dominions. But, 
by every addition to the powers of the other in- 
Btniment, we see each part of them more crowded 
than before with the wonders of his unwearying 
hand. The one is constimtlf widening the circle 



of hb tenitoiy. The other is as constantly fill- 
ing up iU separate portions with all that is rich, 
and various, and exquisite. In a word, by the 
one I am told that the Almighty is now at work 
in regions more distant than geometry has ever 
measured, and among worlds more manifold than 
numbers have ever reached. But, by the other, 
I am also told, that, with a mind to comprehend 
the whole in the vast compass of its generality. 
He has also a mind to cbncentrate a close and 
separate attention on each and on all of its par- 
ticulars ; and that the same God who sends forth 
an upholding influence among all the orbs and 
movements of astronomy, can fill the recesses 
of every single atom with the intimacy of his 
presence, and travel, in all the greatness of his 
unimpaired attributes, upon every one spot and 
comer of the imiverse he has formed." — Ohal- 
mers^s Astronomical Discourses, 

For the introduction of a passage so long, and 
so well-known, the reader will find an apology 
in its great beauty and appositeness. It may 
also be added, that it would be impossible to sup- 
ply a more appropriate preface to the subject of 
the following pages. It is a link of exquisite 
workmanship, connecting the two parts of this 
httle volume. 




A MICROSCOPE is an optical instrument, by which 
very small objects are magnified. By means of 
it many discoYeries have been made, which are, 
in some respects, even more wonderful than those 
oi the telescope. We naturally associate ideas 
of magnitude with power; but to discover the 
infinite in the invisible, not because it is remote, 
but because it is too diminutive to be discerned, 
baffles all our attempts to '* find out" Him whose 
greatness is as unsearchable in the minute as in 
the mighty. 

Invention of the microscope. — ^The microscope 
appears to have been invented not long after the 
telescope^ and it is probable that the invention 
of the one instrument led to that of the other. 
All that we can be assured of is, that micro- 
scopes were first used in Germany, about the year 
1621, or nearly twelve years after the invention 
of the telescope. According to Borellus, who 
gives the most particular details of its invention, 
we are indebted to Zachary Jansen and his son 
for the microscope. Others, however, claim the 
honor of inventing it, particularly CQr\3L<&lv\3& I^\<6- 


bell, a man of science and ingenuity, who invented 
the thermometer; and Fontana, who professed 
that he made the discovery in 1618, although he 
published no account till 1 6 4 6 . Borellus informs 
us that the Jansens presented the first micro- 
scopes which they made to Prince Maurice and 
Albert, Archduke of Austria. A minute descrip- 
tion has been given of these instruments, from 
which it is evident they were either compound 
microscopes, or telescopes adapted to the exami- 
nation of near objects by a different arrangement 
of the glasses. In No. 42 of the " Philosophical 
Transactions" of the Royal Society for 1668, 
we have an account of a microscope made by 
Eustachio Divini, at Rome, which consisted of 
two plano-convex glasses, so placed as to touch 
each other in the middle of their convex surfiEice. 
It is described as sixteen inches long, the eye-glass 
almost as broad as the palm of a man's hand, 
and the tube in which it was inclosed almost as 
thick as a man's leg ; it was adjusted at four dif- 
ferent lengths — in the first, which was the leasts 
it showed objects forty-one times larger than to 
the naked eye, in the second ninety times, in the 
third one hundred and eleven times, and in the 
fourth one hundred and forty-three times. 

About the period now referred to, M. Hart- 
soeker proposed using smaW ^loWlea of ^lass. 



instead of lenses. A microscope, containing a 
globule one tenth of an inch in diameter, may 
be demonstrated to have a magnifying power of 
one hundred times in diameter. Were it not for 
the diflSculty of applying objects to these magni- 
fiers, the want of light, and the small field of dis- 
tinct vision that can be obtained in them, they 
would perhaps be the most perfect of single mi- 
croscopes, since they could be made to magnify 
above three hundred times ; but they are now sel- 
dom used. Few distinguished themselves more, 
in the seventeenth century, by their microscopical 
observations and discoveries, than the famous M. 
Leuwenhoek, a native of Holland. His micro- 
scopes all consisted of small double convex len- 
ses, set in a socket between two silver plates 
riveted together, and pierced with a small hole ; 
and the object was fixed on the point of a 
needle, so contrived as to be placed at any distance 
from the lens. These microscopes were be- 
queathed to the Royal Society, and on examining 
them it was found that the highest magnifier in- 
creased the diameter of an object one hundred 
and sixty times, but that all the rest fell much 
short of that power. 



General description of Microscopa. 
A brief description will now be given 

which are most simple and most eoiumonly used. 
1. The single mia-oscope. — Tliis amplest o( 
Oill microscopes is nothing more than a con- 
vex lens, whose focal distance is extremely aliod 

Let A B, 6g. 18, be a double conrex lens, y « 
llie object at its focus c, g the eye very near thfl 
lens A B ; the rays coming I'rom the object will, 
after their refraction, fall panillel upon the eye, 
and, consequently, make distinct vision. There- 
fore, a minute object e f, seen distinctly through 
a small glass lens t. n, by the eye put close lo it, 
a,ppears so much greater than it would to thp 
naked eye placed at the distance n d, as this dis- 
tance is greater than s c. To illustrate Ibis, let 
us suppose the focal distance of the glass a b to 
be half an Inch, and tlie distance b d eight inohea. 
the usual distance at which we view minute ob- 
jects, then the object may be said to be magoi- 
Sed as ranch as eiglil lucVea cxoee4 Oat w 
e a c, or iLu focul dwUnce ot xJ 




that is, in the proportion of sixteen to one, or six- 
teen times. If the focal distance of the lens were 
one-fifth of an inch, the magnifying power would 
be forty times ; if one- tenth of an inch, eighty 
times ; and if it were one-twentieth of an inch, the 
diameter of any object would be magnified one 
hundred and sixty times, which is found by divid- 
ing eight inches by the focal length of the lens, 
8-r^iP=160. The surface of the object will, of 
course, be found by multiplying the diameter into 
itself, which produces twenty-five thousand six 
hundred times ; and the solidity or bulk would be 
magnified four million and ninety-six thousand 
times, that is, the surface multiplied by the diame- 
ter. A angle microscope may be represented by 
^. 19, where y is the lens fixed into a socket 
with- a handle, a e a small object placed at its 
focal distance from the lens, and a e the magnified 
picture of the object. 

Fig. 10. 


The performance of the single microscope d 
pends, in a greai mensure, on the Qlearneas nod 
purity of the glass of which it la made, and oa 
the ttcouraoy with whicli it is polished, sd aa to 
tcep it of a true spherical Sgure. Wben eim> 
pklL'd — that is, when ground and polished— ft 
should be as thin as it can possibly be rendered 
with a sufficient aperture. When a lens is thak, 
approaching to the figui'c of a globe, it is not so 
tiansparent as when thin, and the field of view 
at the edges is partiy distorted. And it must 
be of a sufficient diameter or aperture, that the 
eye may take in a moderate Geld of view, and 
Lhat there may be as little deficiency of light aa 
possible. Lenses hai-e been made whose focal 
length did not exceed one-fortieth, one-fifdelb, 
or one-sixtjetii of an inch ; but such high powers 
are difficult to be used. Sir D. Crewslcr has 
remarkf d, that " we cannot expect any essential 
improvcmeat in the single microscope, uoleas 
from the discovery of some transparent substatKOi 
which, like the diamond, combines a high re- 
fractive power with a low power of ilisperaion," 
In corrL'hpondencc with this suggestion, the ^a- 
mor^ h-is been of late years formed into lenue 
by. Mr. Pritchard, of London. The first diamond 
Jeps was completed at the end. ot \%'I4, and }m 
succeeded in finishing the fits*. iianioTii iimsto- 



scope in 1826. The focal distance of this mag- 
nifier, Tvhich was double convex, is about one- 
thirtieth of an inch. The principal advantages 
of employing diamonds in the formation of micro- 
scopes, arise from the naturally high refracting 
power they possess, by which we can obtain 
lenses of any degree of magnifying power, with 
oomparatiyely shallow curves. The indistinct- 
ness occasioned by the figure of the lens is thus 
greatly diminished, and the dispersion of color 
in the substance being as low as that of water, 
renders the lens nearly achromatic. Mr. Prit- 
chard has also formed lenses of sapphire and 
other precious stones, but they are not prefera- 
ble to the diamond. The following table ex- 
hilHts the magnif3ang powers of Mr. Pritchard*s 
sapphire microscopes : — 




Magnifying Power. 


Magnifying Power. 


















I \Q^,^^^ 


\ UQ<^^^ 




In mounting the diamond and sapphire lenses 
there are advantages which glass lenses do not 
possess. Their extreme hardness enables them 
to be burnished with brass settings, which is 
very difficult with those of glass. This facility 
of mounting renders them more extensiyely 
useful in experimental researches, from their 
capability of being applied in every possible 
way with regard to the object, the light, or the 
eye. But it is evident that such lenses, both 
from the difficulty of grinding and polishing, 
and from the costliness of the material, muBt be 
very expensive. 

There are various simple methods of procuring 
small lenses for microscopes, some of which 
may be here stated/ Take a small slip of win- 
dow glass, about one-tenth of an inch broad; 
melt it in the flame of a lamp, then draw it oat 
into fine threads, then hold one of these threads 
with its extremity in or near the flame, till it 
runs into a globule. The globule may then be 
cut off and placed above a small aperture, so 
that none of the rays which it transmits pass 
through the part where it is joined to the thread 
of glass. Lenses composed of fluids have also 
been made, which are frequently useful where 
better microscopes are not at hand. Take up 
a drop of water on the point of a pin, and place 


It in a small hole in a thin piece of brass^ about 
one- twentieth of an inch in diameter. The hole 
should be in the middle of a small spherical 
eayity, about one-seventh of an inch in diameter, 
and a little more than half the thickness of the 
brass, which should not exceed one-sixteenth of 
an inch in thickness. On the opposite side of 
the brass should be another spherical cavity, 
half as broad as the former, and so deep as to 
reduce the circumference of the small hole to a 
sharp edge. The water being placed in these 
cavities will form a double convex lens with 
unequal convexities, which will produce' a pretty 
high magnifying power. A better substitute 
for water is a drop of very pure and viscid 
turpentine varnish, which may be taken up on 
the point of a piece of wood and dropped upon 
a piece of thin and well-polished glass. Sir D. 
Brewster describes the following as the best 
method of constructing fluid microscopes : — Take 
Canada balsam, castor oil, or pure turpentine 
varnish, and drop either of them on a piece of 
glass, the surfaces of which are parallel, when a 
plano-convex lens will be formed. Their power 
may be varied by the quantity of the fluid em- 
ployed, or by allowing the plate of glass to be 
horizontal with the drop above or beneath it : 

if the plate be uppermost, the gr«N\V3 ^^ ^^^^ 



fluid will make it more convex ; if the drop be 
above tbe plate, the lens will be flattoied. 
When turpentine is used, it soon becomes indu- 
rated, and, if kept from dust, very durable. Sir 
David informs us, that he has made both the 
object and eye-lenses of compound microscopes 
in this manner, which performed extremely well, 
and lasted a considerable time.^ A single re- 
fleeting microscope may be formed by i^ concave 
speculum, having the object placed on its axis, 
and nearer to the surface of the reflector than 
the focus, when an enlarged view of the object 
will be seen on looking into the mirror. This 
instnunent may be employed to enable a person 
to view his own eye, and will show a magnified 
representation of the ball, the pupil, the iris, 
and the ramifications of the blood-vessels. On 
the same principle, if the reflector be large, for 
example, six inches in diameter, the whole head 
and face may be seen magnified three or four 
times in length and breadth, and above tien 
times in suiface. There is a species of lens, 
sometimes called the Coddington lens, formed 
of a piece of glass nearly half an inch in thick- 
ness. The upper and lower surfaces are convex. 
The sides are hollowed out, giving the lens 

^ Treatise on New Philosopliical Instruments, pagei 
414, 416. 


somewhat the shape of an hour-glass, and re- 
ducing the stem to a very small size. These 
lenses are of a very short focal distance, have a 
great magnifying power, and serve either as 
single microscopes, or for the object-glasses of 
compound ones. 

There are various modes of fitting up single 
microscopes, some of which are complex and 
expensive. The following plan may be recom- 
mended as both simple and convenient. Fig. 20 
(p. 100) represents the mounting of a single mi- 
croscope. K represents the box containing tho 
whole apparatus. On its top there is a hollow 
screw, for receiving the screw that is in the 
bottom of the pillar a. d is a brass pin that 
fits into the pillar. On the top of this pin is a 
hollow socket to receive the arm that carries 
the magnifiers ; the pin is to be moved up or 
down to adjust the lenses to their proper dis- 
tance from the object, e the bar which 
carries the magnifying lens, which fits into the 
socket X. This arm may be moved backwards 
and forwards in the socket x, and sideways 
by the pin d, so that the magnifier, which is 
screwed into the ring at the end e, may be 
easily made to traverse over any part of the 
object that lies on the stage or plate b. f f is 
a polished silver speculum, with a c.otc^%^\k«^ 


plftced at 11 LLi t (\1 h L J ^ hJ for this 
purpose, riie sUter Bpeculum sciens into tbe 
arm e, as at f h th« semicircle which Eupports 
the mirror i e the stage or the plane on which 
tlie objects are to be placed, l a pair of nippen 
which are fixed on the stage by the pla k 
ivory slider which occasionally screws te J 


point of the nippers. The silver speculum is 
intended to throw light on the upper surface of 
an opaque object ; but when transparent objects 
are viewed, there are other lenses which may 
be used without the speculum. Additional 
apparatus is connected with this and other 
microscopes, which it is unnecessary here to 

2 . The compound microscope. — ^When a micro- 
scope consists of two or more lenses or specula, 
it is called a compound microscope. In this 
microscope the im>age is contemplated instead of 
the object ; one of the lenses of which it is com- 
posed forms an image or picture of the object, 
as in the telescope, and this image, in a magni- 
fied state, is viewed by an eye-glass, which pro- 
duces an additional magnifying power. Let l n, 
^g. 21, (p. 202,) represent a double convex lens, 
and o B a small object, so applied that the pencils 
of rays which emerge from it and pass through 
the lens may converge to their respective foci, 
and form an inverted image at i m. This image 
will be so much larger than the object, in pro- 
portion as its distance exceeds that of the object 
from the lens. For example, if the distance of 
the lens l n from the object o b be half an inch, 
and the distance l m, where the image is formed, 
be seven inches, the image wJft. \» toxsNftws^ 



times larger than the object ; and if it be vien 
through the lens f o, which suppose to be i 
inch, it will ag^ be magnified eight times, 
the prindple of the single microscope, and i 
whole magnifying power will be 8X14=] 
times. But the pencil of rays emitted fron 
in the object, and made to converge by the 1 
to M, proceeds afterwards diverging towards 
and, therefore, nerer arrives at the lens 7 a, i 
enters the eye at e. Oii\y XVb i«,^«^!D^-\RQa 


from the poiats o and ft will be received o 
lens s a, and by it be carried to the eye ; the 
parts of the imnge i and ni will be yisible, but 
those situated towards i and m will not be seen. 
This quanUty (i in) of the image i -a ia called 
the _fieM of vtew, which is comparatively small 
when only a single glass is used. In order to 
enlarge the field of view, it is requisite that a 
broad lens, s e, fig, 22, be interposed at a small 
distance from the focal image ; for by tbat means 
the pencil a m, which would otherwise 113ve pro- 
ceeded towards h, is refracted to the eye, as 
shown in the tigure. In the same manner, the 
other extreme of the imag'e is seen at q, and the 
intermediate points are ulso rendered visible. 
On these oonsideratJons it is that compound 
microscopes are usually made to consist of an 
object lens, l s, by which the image is forined 
and enlarged, na amplifying lens, d b, by which 
the field of view is enlarged, and an eye-glaaa, 
F c, by which the eye is allowed to approach 
very near, and to view the image under a great 
angle of apparent magnitude. For similar rea- . 
sons tliree, and sometimes fom' eye-glasses s 
Bubstituted in place of the amplifying lens. 

Having briefly described the theory and pria-1 
'■ ciple of this microscope, we shall now pve a 
description of the finished inGlmmc'cA, w\& 'Cuk 


way in which it is used. The large figure, fig. 
23, represents the body of the microscope ready 
for use, which, including the pedestal, is from 
twelve to fifteen inches in height. In this figure 
it is represented as consisting of three tubes. In 
the large tube, a, the smaller one, b, slides up 
and down. At the upper part, a, one or two 
eye-glasses are contained, and at some distance 
beneath them the amplifying lens is placed. At 
the lower part, 6, the object-glass is placed, %nd 
the small tube which contains it is connected 
with the tube b, by which it is made to slide up 
or down, to adjust the focus to the eye. Below 
the object-glass is c, a kind of spring to receive 
the stiders, which may be occasionally taken out, 
and a plane glass laid across the opening in the 
stage on which any small object may be laid. 
D is the pedestal on which the instrument stands, 
c is a glass concave mirror, which turns in all 
directions, to reflect the light from a candle, or 
from a window, through the hole c. Fig. 24 
represents nippei's for holding insects, or other 
small objects. Fig. 25 is a small glass tube, 
capable of containing a live fish, when observing 
the circulation of the blood in its tail. Fig. 26 
repesents one of the sliders for holding objects, 
vhich are placed between two pieces of talc, or 
two thin slips of glass. Fig. 2*1 laalxoWo^ <iQV!^^^ 


to be placed occasionally under the stage d, to 
diminish the quantity of light. Fig. 28 is a pair 
of brass forceps, to take up a minute object 
Fig. 29 represents a round piece of glass, to 
which is fitted a concave glass, for the purpose 
of confining animalcules, and other small living 
creatures, for minute inspection. 

Compound microscopes have been much im* 
proved of late, by using small achromatic lenses 
foi-^the object-glasses. They have been made 
as small as one-fifth, one-fourth, one-half, and 
one inch focal distance, and sometimes two or 
three of them are occasionally combined together, 
which produces a very high magnifying power, 
with great distinctness. But such lenses add 
considerably to the expense. About ten yean 
ago £1 3«. was the cost of one of these lenses 
one and a quarter inch focal distant, and those 
which were of a shorter focal distance were 
charged at two guineas and upwards. A person 
who feels himself unable to purchase an expen- 
sive compound microscope, may construct a 
pretty powerfid one for a few shillings, by at- 
tending to the following directions : — Procure 
for the object-glass a lens about half an inch 
focal distance ; another for the amplifying lens 
two and a half inches focal length and one and a 
half inch diameter ; aivd a third ^lass one inch 

107 ^H 

distance, to be placed next the eye. The 
at which these glnascs should be placed 
each other are as follows : — The object- 
half an inch focal distance, should be 
i at the end of a small tube nest the 
jcct, and the aperture or hole that lets in the 
"it should not eiceed one-tenth of an inch in 
meter. At the distance of about seven inches 
B this glass the nmplifying lens should be 
Midi and the glass next the eye, one inch focnl 
Ijuioe, ehould be placed about one and three- 
.n inch from the amplifying lens. 
lb a microscope, reckoning the combined eye- 
gses to magnify the image six times, and tho 
ject-glass to magnify the object fourteen times, 
" produce a magnifying power of eighty-four 
B ui lineal dimensions, and in surface seven 
busand and fifty-six times — a power which will 
ow a small creature, such as a flea, as if it were 
[ht and a half inches long and of a. eorrespond- 
f breadth, and will bring to view all the larger 
ecies of animulcules. The stage and its sup- 
irta may be made of wood, and the tubes of pa- 
rot very tlun pasteboard. The tube 5,{p.l04,) 
which the eye-glasses are placed, should be 
kde so as to pull out occasionally, to increase 

between the eye-g\aaaea awi fee- 
tet-ghae, and consequently t,\\e TOao;E&"3\'wf, 



power. Any person with mechanical talent 
easily make such an instrument at a trij 
expense. The compound microscope is n 
pleasing in its use than the single microscc 
it has a larger field of view, and the eye is 
so much strained as in looldng through i 
small lenses. 

3. The solar microscope, — This microscop 
constructed in the following manner. Ii 

Fig. 30. 

closed window shutter, or in a board fitted 
the window, make a hole about three inche 
diameter, through which the sun may cac 
cylinder of rays, a a, into the darkened ro 
^^, 80. Into this hole place the end of a ti 
containing two convex glasses and an obg 
namely, a convex glass, a a, of about two inc 
diameter and three inches focal distance, is t( 
placed in the end of the tube, which is put 
the hole. The object, b b, \& ^\sa^ ^\^Q^t 


nd a half inches from the glass a a. If the 
bject be a living animal it must be put between 
wo concave glasses. A little more than a quarter 
f an inch from the object is placed the small 
onvex lens c c, whose focal distance may be 
bout a quarter of an inch. The tube may be 
o placed, when the sun is low, as that his rays, 
. A, may enter directly into it ; but when he is 
ligh, his rays, b b, must be reflected Into the 
ube by the plane mirror c c. Things being in 
his state, the rays that enter the tube will be 
onveyed by the lens a a towards the object b b, 
\Y which means it will be strongly illuminated, 
nd the rays d, which flow from it through the 
VOM e €, will form a large inverted picture of the 
bject at D D, which being received on a white 
yreefn, will represent the object magnified in 
mgth, in proportion of the distance of the pic- 
ire from the glass c c to the distance of the ob- 
ust from the same lens. Thus, suppose the dis- 
ince of the object from the lens to be half an 
icb, and the distance of the image fourteen feet, 
r <me hundred and sixty-eight inches, the object 
fill be magnified in length and breadth three 
nndred and thirty-six times, and in surface one 
andred and twelve thousand, eight hundred 
nd ninety-six times. 
In fig. 31, some of the parts of this instrument 


are more particularly represented. The sq 
plate, b c d, is attached to the wmdow shi 
by the screws ef. The mirror g is mount6( 
a wooden frame, and may be elevated or 
pressed by a screw at d. A rotary motk 

communicated by a pinion and handle $i c. ' 
first lens is placed in the tube a, immedisi 
adjoining the mirror. Another tube, m, Ib 
tached by a screw at n, and contains the oi 
lenses for magnifymg the object, and the n 


work k I for adjusting the' focus of the instru- 
ment. The objects are introduced at i. When 
lenses of high power are employed at A, they 
are now constructed on the achromatic principle. 
This instrument is not so much used as for- 
merly, in consequence of the invention of the 
oxyhydrogen microscope, which is not depend- 
ent on the sun, but may be used either by day 
or by night, provided the room be darkened, 
the oxyhydrogen light being substituted for that 
of the sun. This is the microscope which is 
now exhibited in lecture-rooms, and in our Poly- 
technic Institutions. It may not be improper 
here, to give a hint to some persons not much ac- 
quainted with such exhibitions. One of the ob- 
jects shown by this microscope (the oxyhydrogen) 
is the appearance of a heterogeneous mass of 
animals, which appear to be fighting with each 
other on a very large screen, intermixed with 
T^etable fibres. It has been taken for granted 
by some spectators, that these animab were all 
contained in a drop or two of water, and that 
they consorted together in the manner repre- 
sented. This is by no means the case ; no such 
associations are to be foimd in the animalcular 
world. A number of small animals of dififerent 
kinds, most of them visible to the naked eye, 
are collected by the exhibitors, and put into a 


small glass vessel, perhaps an inch or two in 
diameter, along with water and a few vegetable 
fibres. It forms a strildng exhibition, but p^- 
sons should beware of deducing from it erroner 
ous conclusions. 

4. The lucerrud microscope. — This instniment 
was invented by Mr. George Adams, an optician 
in London. It consists of a hollow pyramidal 
box of mahogany, which forms the body of the 
microscope. Fig. 32 exhibits a view of this in- 
strument, mounted to examine opaque objects. 
6 is the large pyramidal box, supported firmly 
on the brass pillar n, by means of the socket m 
and the curved piece e, a is a guide for the 
eye, to direct it in the axis of the lenses ; it con- 
sists of two brass tubes I, one sliding within the 
other, and a vertical flat piece, at the top of 
which is the hole for the eye. The inner tube 
may be pulled out or pushed in, to adjust it to 
the focus of the glasses. The vertical piece 
may be raised or depressed, that the hole through 
which the object is to be viewed may coincide 
with the centre of the field of view. At the 
small end of the cone is placed a tube, whieh 
carries the magnifiers, one of which is repre- 
sented at c ; the tube may be unscrewed occa- 
sionally from the wooden body. Beneath the 
cone is placed a long square bar, which paaeei 


through, and carries the stage or frame that 
holds the object ; this bar may be moved back- 
wards or forwards, to adjust it to the focus, by 
means of the pinion k. A handle, with a uni- 
versal joint for turning the pinion, is shown at o. 
The stage h, for opaque objects, fits upon the 
bar by means of a socket, and is brought nearer 

Fiff. S9. 

to or farther from the magnifying lens by tum- 
mg the pinion h. At the lower part of the stage 
there is a semicircular lump of glass, g, which 
ifl designed to receive the light from the lamp, 
and to throw it on the concave mirror/, whence 
it is reflected on the object. The upper part of 
the ojmque stage takes out, t\^t \\i^ %Xaj^^ Vst 



transparent objects may be inserted in its place. 
Between the exterior of the two lenses at the 
larger end and the eye of the observer, th^ie is 
placed a plate of glass, rough ground on one 
side, which serves as a screen to receive the rays 
of light proceeding from the object whose repre- 
sentation is to be viewed. An Argand lamp, or 
the oxyhydrogcn light, is placed beyond the ob- 
ject, before the glass lump g. 

By this instrument, opaque objects may be 
seen with ease and distinctness. The beautiful 
colors ^vith which most of them are adorned are 
rendered more bnlliant, without changing in the 
least the real tint ; and the concave and convex 
parts retain also their proper form. The facility 
with which all opaque objects are applied to this 
instrument is another considerable advantage, 
and one almost peculiar to it. The lucenud 
microscope does not in the least fatigue the eye ; 
the object appears like nature itself, giving ease 
to the sight and pleasure to the mind ; and there 
is no occasion to shut the eye that is not directed 
to the object. The outlines of eveiy object may 
be taken even by those who are not accustomed 
to draw, while those who can draw well will re- 


ceive great assistance. Transparent objects as 
well as opaque may be copied in the same man- 
ner. This instrument may \)^ \i&ed ^t any time 


oi the day, but the best effect is by night, in 
which respect it has a superiority over the solar 
microscope, which can only be used when the sun 
shines. Such are some of the properties of tbe 
lucenud microscope, as stated by the inventor. 

Besides the microscopes we have already de- 
cribed, different forms of this instrument have 
been constructed on the principle of reflection, 
by a combination of speculums both convex and 
concave. These microscopes were constructed 
as early as the year 1738, by Dr. Smith, Mr. 
Baker, and others, but they had been abandoned 
for many years, till, in the year 1815, Amici, a 
Frenchman, directed his attention to their con- 
Btruction, and greatly improved them ; and they 
were still further improved in England by Dr. 
Gonng and Mr. Cuthbert ; but owing to the 
difficulty in constructing the reflectors, and the 
great trouble in managing them, they again fell 
into disuse, and even Amici himself returned to 
htB former experiments with achromatic object- 

If it be asked which of the microscopes now 
described we would recommend for making re- 
searches into the mmute parts of nature, we 
answer, without hesitation, the compound micro- 
dcope furnished with achromatic object-gla^aea, 
Tbe compound microscope as no\Y \m\iiQ)N^, \a 


use the words of an eminent optician, "1 
within the last sixteen years, been elevated fi 
the condition in which it was previously fot 
to that of being the most important instrunQ 
ever yet bestowed by art upon the investigi 
of nature." The application of achromatic 
ject-glasses to compound microscopes has o 
been attempted within the last twenty-six ye 
In 1824, the late Mr. Tulley, of London, 8 
ceeded in making the first English achromi 
object-glass for a compound microscope, 
was composed of three lenses, and was cape 
of transmitting a pencil of rays of 18°. 
soon after constructed another combination 
be placed in the front of the first mention 
which increased the angle of the pencil to S 
Mr. Tulley's object-glass exhibited a flat fi« 
and was perfectly corrected ; to it was app 
an eye-piece, by which the magnifying po' 
produced was one hundred and twenty diamet* 
but when the second combination was add 
the power was increased to three himdi 
These object-glasses have since been impra 
by Messrs. Lister, Powell, Ross, and Sm 
Their focal distances vary from one inch an 
half to one-eighth of an inch, and they may 
used either separately or m combination. Soi 
times tiiree seta of ^eoi «c^ <^csii!^s«^ V^i^ 


which produces a very powerful effect. Mag- 
nifying powers equal to one thousand two hun- 
dred diameters have thus been obtained with 
great distinctness ; that is, the surfaces of objects 
have been magnified one million four hundred 
and forty thousand times. Some of the powers 
thus obtained have been equal to even two 
thousand diameters, and consequently the sur- 
face magnified four million times. But such 
instnunents, as formerly stated, are expensive. 

Objects to which the microscope may he applied. 

Every part of creation demands our atten- 
tion, and proclaims the power and wisdom of 
the Creator. The microscope has shown to 
UB these perfections in objects which the unas- 
sisted eye has never seen, no less than in those 
which may attract our notice in all the walks 
of life. It has unfolded to our view wonders 
unknown and unthought of in former ages. 
Three hundred years ago, who would have 
conceived it possible to distinguish myriads of 
living creatures in a single drop of water ? Or, 
that blood could be distinctly seen circulating 
through the veins and arteries, smaller than the 
finest hair? Or, that not only the exterior 
form, but even the internal structure of the 
visoera, and the motion of the VxvWiox ^^^> 


sLouid be rendered perceptible to the aght? 
Or, that numberless species of animnted bcingi 
should he mcide visible to the eye, though so 
minute that a million of them are less than b 
grain of sand ? 

The various sections of animal and vegetable 
life are full of beauty, and in their minutest de- 
tails exhibit a completeness and a finish infinitelj' 
transcending tlie most exquisite and ndtnlred 
pieces of art. The scale of a sole, so small as to 
be overlooked by us, is a work of moat admintbiB 
regularity and delicacy. It is a kind of wch, 
with a number of small points at one end, 
which fasten it to the hack of the fish. TilVK 
is not a singie fish whose scales are not inora 
beautifully woven than any texture whioh ia 
found in the finest handiwork of man. The 
fibres that compose the scale of a pike are 
formed in a manner quite different from those 
we admire in the scale of a cwrp or a perch; 
still one order is invariable in all the scales <rf 
the same species. Equal regularity b found in 
tlie structure of the feathers of birds, in the 
fibres of the flesh of animals, in the grain of the 
several kinds of wood, and in the figui'es of the 
tJ'ifferent salts. The dust on the wing of a 
moth or a bullerfly. a single ^omXAe <A -wVuio, 
M so minute as to be m-vi*ib\e,"\a lo-aRa.. -*»« 


magnified, to be a beautifully-formed feather, 
and exhibits the most delicate and admirable 
arrangement in all its parts. In a moth there is 
a configuration entirely distinct from that of a 
butterfly ; each species has feathers of a different 
form from those of another. The same variety 
and exquisite mechanism prevails in every de- 
partment of the vegetable kingdom. 

The following objects, among many others, 
may afford amusement and instruction to those 
who are possessed of microscopes : — ^the scales 
of fishes ; the dust on the wings of butterflies, 
moths, gnats, flies, and other insects ; the flea, 
and mites in cheese ; the eels, serpents, or little 
worm-like animals found in vinegar and paste ; 
the animalcules existing in infusions of pepper, 
as well as of hay, grass, flowers, and other vege- 
table substances ; the eye of the house-fly, the 
dragon-fly, and of various other insects; the 
legs of spiders ; the claws of beetles ; the wings 
of small flies ; the eye of a lobster ; slices of 
broom, lime-tree, dogwood, and oak ; transverse 
sections of plants of various kinds, every one of 
which has a different configuration from an- 
other ; the farina of flowers, particularly of the 
sunflower; the leaves of trees, plants, and 
flowers ; the fibres of a peacock's feather, and 
the feathers of other, birds ; the hnm&xv \v^x \ 


the hair of a mouse, ajid llie hair of on Indite 
bat ; the sting of a bee or a wasp ; the stings d 
a nettle ; small files which infest fruit and trees; 
the beard of a wild oat ; seeds of poppies tmd 
other small seeds ; mouldiness, which is a spe- 
cies of vegetatiim, or a forest of mushrooms; 
the small nimble insects existing among pinb, 
roses, and sunflowers ; water spiderE^, not la>^ 
than a grain of sand, found in ditehes : the silk- 
worm in its rarious transformations ; the njmph, 
aurelia, or chrysalis of moths, butterflies, and 
other insects ; the proboscis of a butterSy, 
which winds romid in a spiral fonn like the 
spring of a watch, serving both for mouth and 
tongue ; mosses of all kinds ; sponge, reckoned 
a plant-animal, composed of minute vessels m- 
sembling veins and Ftrteries ; grains of sand, 
which are of vanoua forms, having al! numeroos 
sides and angles, some of them finely polished ! 
the flakes of snow before they melt : the tmls of 
fishes, the flns of water-newts, and the webs 
between the toes of frogs, in which the droa- 
laljon of the blood may be beautifully seen ; and 
fresh-water polypi, witli arms in theform of lionw. 
The above are only a few specimens of ta& 
thousand objects in the minute parts of creatJon, 
which display beauties, contrivances, and in- 
MtaaetB ej ditine meehaiusm. of ^luefa va- 


who has not looked at them through the micro- 
scope can form any adequate conception. There 
is, in fact, scarcely a particle of matter in crea- 
tion, in which this instrument does not show 
something worthy of being admired. In addi- 
tion to natural objects, however, we may further 
mention the following artificial productions, 
which afford entertaining materials for micro- 
scopic observation. 1. The silver- tree ; the pre- 
paration of which is as follows : — Dissolve a little 
silver in a small quantity of aquafortis ; thpn 
add twice the quantity of common water to it. 
When it is applied to the microscope, a little of 
it should be dropped on a plane glass, and a 
short piece of small brass wire put into it ; imme- 
diately trees will appear growing, till they have 
spread as far as the liquid extends. 2. The 
eryiiallizaiion of salts : — Dissolve a little sal- 
ammoniac in common water, place it upon the 
glass as stated above, and while viewing it, 
hold a hot iron near the glass, in order to make 
it more expeditious in evaporating. As soon 
as evaporation takes place, appearances are pre- 
sented like the branches of trees, in the most 
beautiful variety. Every different kind of salt 
forms a new arrangement and a different figure. 

Among the multitude of ob^eeXfe -w^kvs^ \i^\xsK. 
preaenta for the employment o< ^"fe xmvrx^^^^^'V^^ 


our limi'^ wiil p-erz:;: us lo select only a few f< 
pfjfilf.-.-'ijr DOiic*. Wc shall commence with 
descripiion of a few species of 

AyiMALcuLE?. — Pnis lerm is now general]; 
used to distinofuish animals of a size so diminn 
live that their true figure cannot be discerned 
without the assistance of glasses; and mor 
especially, it is applied to such as are altogethe 
invisible to the naked eye. By the microscop 
we are brought into acquaintance with nei 
tribes of the li\'ing world, and innumerabi 
animated beings, which, from their minuteness 
would without it have escaped our observation 
How many of these invisible tribes there noay b 
throughout the air, the waters, and the earth, i 
still unknown, but they doubtless far exceed th< 
number of all other classes of li\ing creature 
combined. To know that there are myriads oi 
atoms, endued with vitality, existing in a singk 
drop of water, executing all their various func 
tions and evolutions with as much rapidity anc 
case as if the range afforded them were bound 
less as the ocean, must powerfully interest ever] 
mind which takes pleasure in the works of God 

It is almost impossible to convey a correct idef 
of the various shapes of these singular forms of 
life to those who have not actually beheld them 
2lHiy appear to have little or no similarity to the 


other diversified orders of animal existence. 
Some of the smallest appear merely like moving 
points or atoms ; the large ones exhibit an as- 
tonishing variety — some are hke spheres, others 
are ^g-shaped ; some are like hand-bells, others 
are like wheels turning on an axis ; some repre- 
sent fruits and vegetables of various kinds, 
others resemble eels, serpents, and snakes ; some 
are like double-headed monsters, and others like 
cylinders ; some have the appearance of funnels, 
tops, pitchers, and flasks, others are worm-like ; 
some have horns, fins, and feet, others resemble 
small fishes, playing in the rivers or the sea; 
some are like long hairs, a hundred times longer 
than they are broad, other are like spires and 
enpolas ; some of them are almost visible to the 
naked eye, others so small that a human hair 
would cover more than a hundred of them ; while 
millions of millions of them might be contained 
within' the compass of a square inch. They, 
however, possess {Peculiar habits, adapted to 
their respective forms. While some move 
through the water with the greatest rapidity, 
darting, leaping, or swimming, others creep or 
glide along, and many are so passive, that it 
requires patient observation to discover any of 
their movements. We may now give a brief 
description of some individual speciea of auimal- 


1. The Monads. — This genus of animalci 
includes the smallest forms in which a volunt 
motion has heen observed under the most po¥ 
ful microscopes. Motion appeared to be 
only property of life they possessed, till 
Ehrenberg, an eminent observer of animalci 
existence, demonstrated an organization equi 
perfect with creatures of much lai^er dimensi< 
Their forms are spherical, or cylindrical, and t; 
are colorless, and transparent as the clearest ci 
tal. They increase by a spontaneous division 
the parent into two or more parts, and these p 
again divide, as do also the young when i\ 
have attained their full size. These animalci 
are chiejfly interesting from their extreme mini 
ness. They form the limit of man*s acquaints 
with animated nature. Their diameters vary fi 
the twenty-four thousandth part of an inch to 
twelve hundreth. What is called the end ma 
is so very minute that its existence cannot be < 
covered in the best instruments with a less po^ 
than four hundred linear, or one hundred i 
sixty thousand times in surface. They are ol 
so abundant on the surface of infusions that mi 
millions in a single drop may be taken up on 
head of a pin. If we take some of these anin 
cules, and suppose them to be arranged u 
]me of only one incb in lengtb, it \70uld reqi 


nine thousand six hundred to fonn it ; so that a 
cubic inch would contain eight hundred and 
eighty-four thousand seven hundred and thirty - 
m millions. Some of these monads are found in 
▼aiious vegetable infusions, and are very numer- 
0118 about the infused stalks of the spider- wort.* 
2. Animalcules found in infusions of pepper, — 
If the bottom of an open vessel be covered to 
the depth of half an inch with black pepper, 
grossly bruised, and rain or river water be poured 
in until it rises above the pepper about an inch, 
and if the water be well stirred and exposed to 
the air, in a few days a little pellicle or skin will 
be perceived on its suiface. This skin, examined 
by the microscope, will be found to contain mil- 
lions of animalcules, scarcely discernible at first 
by the greatest magnifier, but continually growing 
la^r, till they attain their full size. Their 
nombers, too, will every day multiply, and at 
length the whole fluid will seem alive. About 
the quantity of a pin's head of this scum, taken 
up with the point of a pen, or a small hair pencil, 
and applied to the microscope, will show several 
sorts of animalcules, differing both in size and 

°For a more particular account of these minute 
animalcules, and their different species, the reader is 
referred to "Pritchard's Natural History of Animal- 


in ah«pe. The following iire somi? of their 
varieties ; — 

Fig, 33 represents the largest kind. Tin 
length of the body is about the diameter of a 
small hair, and three or four times more than Ha 
breadth. It ia very thin and transparent, but 
that side which appears to be tbe back is darker 
than the other. They frequently turn themselves 
in the water, and show both faaek and belly, aa 
seen in figs. 1, 2. The edges of the body are 
fringed with a groat number of exceedingly mi- 
nute feet, which are chiefly perceptible about l^e 
two extremities. At one end, there are likewise 
some bristles, longer than the feet, resembling « 
tail. The motion of these animalcules is swift; 
and by their turns, returns, and sudden slope, 
they seem to be continually hunting about fv 
their prey. They cnn employ th«r feet ia run- 
ning as well as in swimming ; for, on put^Dg R 
hair among .them, they often creep along it from 
end to end, bending in several strange postoiM. 

There is another kind of animalcule in this 
infusion, whose length is about onc'third of a 
hair's breadth, with tails five or six times as Img 
and sometimes longer. Kig. 34, No. 1. exhituts 
one of them with the tail extended. No. 2 re- 
preaeats siiotber of them, w'A\i\te \«i'm «^w,x«m> 
like form, which is very common. Ocswasn^'i, 



when they lie still, tliey thrust out or pull bactr 
again their bearded tongues. A Ihird kim], 
about the size of the last, but -without taiU, ap- 
pear sometimes in an oval shape, tts in fig. If, 
No. 1 : and sometimes a little longer, rusembUng 
» flounder, as So. 2. Their little feet may be 
plainly seen when the water is just evaporating, 
for (hen they move very swiftly. Now and then 
two of them are seen conjoined, as at No. 9. A 
fourth kind appear like slender worms, Bfty ttmea 
as long as broad. Their thickness ia about the 
one-hundredth part of a hair, and they Bwim 
with the same facility backwards as forwardB, 
A fifth kuid is so exceedingly small that a hun- 
dred of ihera in a I'ow would not equal the dla- 
meLcr of a grain of sand, and consequently & 
million of them are but equal to a grain of sand 
in bulk. Then- shape is almost round. 

3, 77ie eeli in pasile and rinegiT, — To prooure 
these, boil a little flour and water, and meh 
paste as bookbinders commonly use. It shottld 
neither be rery stiff nor very watery, but of ■ 
moderate consistence. Expose it to the Open 
air in an open vessel, and prevent its hardening, 
or becoming moldy on the surface, by beating 
it well together. Aftt'T some days it will turn 
sour, and then, if esamined a\:X*.ri>A\c\^, iid^- 
ludes of small, long, riendet, -wti^'^oii% wnmi 


cules will be discerned, which increase daily in 
ate. To promote their deveiopment a. drop of 
Tinegar may now and then be let fall upon 111 
paste. After tlie etls are once produced, th^i 
may be kept ail the year by applying to 

lasionally a. little vinegar and 
may be taken to the microscope on a piece 

! or thin glass, a drop of water for them 

im in being previously provided. They 
Tcry entertaining objects. Sometimes the 
tion of their internal parts may be distiDguisbed. 
la. vinegar itself, after standing a few days UU' 
covered, especially in summer, a epedes of 
will frequently be found. The figure of 
eel-Uke animalcules is shown at fig, 36. 

4. Anrmalcuhg in infmions of ha>j, 
oat*, tslieai, a>id other vegetable produeli 
When the above substances are infused in water, 
aftur some days a sort of wbidsh scum will ap- 
pear upon the surface, which, examined by a 
microecope, will be found to contain an immenae 
number of living creatures, of vuiious sizes and 
forms. The most common is an oval animalcule, 
komewhat in the shape of nn emmet's egg, as 
sbown in fig. 37. They are extremely nimble, 
and in continual motion backwards and forwards; 
but sometimes they stop on a sudden, and t\ 
round on their axis numberless times, and 



i. th^^^_ 
a thM^H 


i«y "fl^l 

luisbed. ' 

of eels 

ternately in diftei-ejit directions, with surprising 

In tlic summer season, the water that Is stag- 
nant in small pools and ditches appeara frequently 
of a greenish, and ocvasionally of a reddish hue. 
On examining it by the microscope, it is found 
that immerse multjtudea of onimnlcules sro 
crowded together on its surfaue, ^vbg it a, color- 
ed appcamnce. The bodies of these animalcules 
are oval, and transparent at both ends, bat tbc 
middle is either green or red. There is reason 
to believe, that in one of those ponds or ditchea 
the number of living creatures enjoying a hap- 
piness suited to their naturiis, exceeds thai of all 
the human inhabitnnis peopling the globe, tba 
liquid whiuli drains from dunghills, presentll^ S 
deep brown color, is sometimes eo thronged trilb 
animalcules, that it soems to be uU alife, Bod 
must be diluted with water before they cwi ht 
sufficiently separated to distinguish their'Turinoi 
kinds. Amoug these is sometimes found a 
species represented in tig. 38. Their middle 
part appears daik, and beset with hairs, but 
both ends of ihem are tinnsparent. Their tsib 
are tapering, with a long sprig at the extremity, 
and their motion is slow and waddling. 

Our limits will not penmt us to prosecute this 
eubjuct much further. We miiy just i-emaric 


that an infusion of any herb, grain, fruit, flower, 
leaves, or stalks of any description of vegetable, 
in common water, will be found, after a few days, 
to contain animalcides in immense numbers, and 
of a species peculiar to the diiOferent substances 
which are infused. M. Joblot, of Paris, has given 
us a description of numerous experiments he 
made on this subject. He examined the infusions 
of pepper — black, white, and long — of senna, 
pinks, blue-bottle, roses, jasmine, raspberry 
stalks, tea, barberries, fennel, sage, marigold 
flowers, sour grapes, mushrooms, and rhubarb, 
and found different animalcules. Hay, new and 
old, abounded with many kinds. Rhubarb, 
mushrooms, sweet basil, and citron flowers, had 
their particular animalcules. The anemone 
afforded a very wonderful species, with a satyr's 
face upon the back. Celery produced many 
kinds, as also did wheat-ears, straw, rye, oats, 
and Turkish com. Oak-bark, new and old, 
afforded great variety. Some of these infusions 
M. Joblot kept a whole year, and observed that 
not only each infusion had animalcules of shapes 
quite different from those in others, but likewise 
that in the same infusion different kinds of 
animalcules appeared at different times. 

5. Description of some animalcules of uncom- 
mon forms. — In all the productions of iva.tMXA 


ihere is a wonderful diversity, particularly in the 
forms of animalcular life. An infusion of ane- 
mone, prepared after tlie oMlioary n 
cold water, at the end of eight days will t^ord 
a new and uncommon aniraaluule, which is repre- 
sented at fi^ 39. All the surface of its back is 
t5overed witli a very fine mask, in the form of b 
kuman face, perfectly well made. It has three 
feet on each side, and a tail coming out from 
under llie mask. Another curious nnimaleide, 
found in an infusion of hay, is represented at 
fig. 40. A shows its head, b its forked tail, c its 
heart, which may bp seen in a regular mo^esa, 
and D its intestines. When this creature reeb, 
it generally opens its mouth rery wide, a 
Ita lips, which it moTes quickly, are fumirfied 
with hairs. There are ringlets lying i 
another round its hod}'. Another animalcolf^ 
which bears a certain resemblance to this, waS 
found in an infusion of pinks, jasmine, and ottiw 
flowers. It is represented at fig. 41. It differs 
from the one above described, in being longer, in 
il3 tail being composed of three points instead 
of two, in hflvmg two little arms, l m, one on eneh 
side of its heart, marked a, in Its intestines, S, 
being without any visible separation, and in 
having neither ringlets, teeth, nor haii« in iU 


Another curious animalcule is found connected 
with duck-weed roots. This little creature is 
represented at fig. 42. It has two wheels, d e, 
with a great many teeth, or notches, coming from 
its head, each turning round upon an axis. At 
the least touch it draws the wheel-work into its 
body, and its hody into a sheath, after which it 
appears as in fig. 48. But when all is quiet, 
it tbmsts itself out again, and the rotation of the 
wheel-work is renewed. One of these animal- 
cules has heen noticed whose case seemed com- 
posed of minute globules, as a, ^g. 44, and in 
this the wheel-work, c, was discovered to con- 
list of four round parts, with little divisions 
between each. In the water of slimy matter, 
found in leaden pipes or gutters, various kinds 
c^ animalcules are discovered, and among the 
rest, multitudes that appear to have a sort of 
wheel-work, turning round in the manner now 

The immense multitude- of these animalcules, 

^ Those who wish a more particular description of 
animalcales, may be referred to Adams's " Microgra- 
phia lUuttrata" his "Essays on the Microscope/' 
Leuwenhoek's " Arcana NeUura^** and Pritchard's 


** Xatoral History of Animalcules/' where there are 
hundreds of figures of animalcules of all forms delin- 

134 THE MroRosropK and itr orjeots. 

the strange forms they assume, the minute ai 
delicate orgcinization of their bodies, and all tl 
mar\'elous diversities of their existence, rend' 
them objects of unfailing interest. In the coi 
templation of these wonders of the divine wori 
manship, indicating the probability of life as f 
below the reach of the microscope as worlds ai 
systems to which the telescope points are abo^ 
its highest range, who does not see that Omt 
potence is as gentle as it is mighty, and as bom 
tiful as it is universal ? 

It will neither be uninteresting nor uninstm 
tive to inquire, whether these minute living aton 
are endowed with that faculty of thought whi< 
is usually described by the word sagacity. M 
Baker informs us, that a small quantity of tl 
matter containing the hair-like animalcules ha' 
ing been put into a jar of water, it so happem 
that one part went down immediately to tl 
bottom, while the other continued floating c 
the top. When things had remained for son 
time in this position, each of these swarms c 
animalcules began to grow weary of its situatio 
and had a mind apparently to change its quartei 
Both armies, therefore, set out at the same tim 
the one proceeding upwards and the other dowi 
wards, so that, after some hours* journey, the 
met in the middle. A w\s\v lo Vxvo^ Vvqst tJhe 


ifToald behave on this occasion led the observer 
to watch them carefully ; and to his surprise, he 
saw the army that was marching upwards open 
to the right and left, to make room for that 
which was descendmg. Thus, without confu- 
sion or intermixture, each held on its way ; the 
body that was going up proceeding in two col- 
umns to the top, and the other journeying in one 
phalanx to the bottom, as if each had been under 
the direction of a leader. '' After viewing ani- 
malooles in a microscope," says a writer, '' I was 
in the habit of returning the drop which contain- 
ed them to the vessel holding the fluid out of 
which it was taken, washing it off the slider with 
a little pure water. On one occasion, I looked 
f\gatn at the sUder through the microscope, and 
foand a little creature m a very small drop which 
had been left behind. Feeling itself somewhat 
confined, it attempted to get out of the drop ; it 
went from side to side, and tried five or six places 
in order to extricate itself from its confinement ; 
but finding no opening, it placed itself in the 
middle, and whirled itself roimd its axis like a 
windmill, till the drop was quite evaporated, and 
Uien, after a few throbs, it ceased to move. At 
another time, I happened to be looking at the 
spots in the sun, and was not a little surprised 
to see one of them, as I sup^jQ6(Qd,ix^QWki^^Rxn^ 

13S TIIR » 

iU disc. Tbis I soon found lo be a small animal, 
about the eize of a mi(«, on one of the glasses <A 
the telescope which I inclosed between Iwo c«i- 
cave glasses. I afterwards watched its move- 
ments through the microscope, and observed 
that it seemed verj- desirous to free itself from 
its coDfinement. It moved first to one poist 
where there seemed a slight opening ; but finding 
none, it tried other apparent crevices ; and when 
at last it gave up its attempts, it returned to the 
centre of its place of confinement. In these 
cases, the little creatures seem to have reasoned 
and acted as rational beings might have dcme in 
similar circumstances." 

Among those who stand foremost in the ranlc 
of microscopic naturalists. Professor Ehrenbei^, 
t« whom we have already alluded, takes the 
lead. In various parts of the I'arlh he has 
studied minute organic productions ; and the 
results of liis persevering inquiries have beeo 
given to the world. His researches, daring 
BaroD Humboldt's last journey, extended to 
more than fifty degrees of longitude, and four- 
teen degrees of latitude. He went us far as 
Dongola in Africa, and the Altai mountaina in 
Asia ; and examined animalcules in a great vsr 
riety of situations. He found them on Momt 


Irells of the Oasis of Jtipitei' Ammon, and at J 
t considerable depth in Rime Siberian mini 
^Boes entirely deprived of light. 

All animalcules were once confounded i 
the name of Infusoria, because they were n 
irith, by their first discoverers, in water & 
tag vegetable matter, or in infusions of vegetabl 
lubstonces. But the propriety of a general ap- 
pellation nill be apparent, when a due considera- 
fion is given to the circumstances in which these 
ttinule bebgs appear. It is an astounding yet 
ir^-attested fact, that organized beings, poa 
MBtng life and all its functions, have been dix ^ 
BOvered so small, that a million of them would 
Oocapy less space than a grain of sand. The 
absolute number of these "miniatures of life" 
hx exceeds tliat of all other living creatures on 
the surface of our globe. 

Their reproduction is perfectly astonishbg. 
En some instances, n single individual gives birth 
to millions in a very short space of time. After 
Qieir death, the accumulation of their shields or 
bard out«r coverings, mixed up with vaHoos 
earthy or flinty particles, produces layers of 
fariouB earths and roclu. These become con- 
■olidated by lime into clays, flints, and marbles, 
a whiob the shape of thek a\\w\46 raA. 'i 
iuaeters are so clearly lo \* ii^itmigN^ 

138 TiiK 


that the very sppcies can 
determioed. The hones 
which razors, penknives, a 
other catting' 
are sharpened, are made of a 
Turkish stone, which is a 
mass of the fossil comenngs 
of animalcules. Tripoli, or rotten-stone, its 
long bBen well knowri in the arts — being used 
in the form of powder for polishing stones and 
nieta.U. It has been procured, among other 
places, from Bilin, in Bohemia; where a nngli 
bed, extending over & wide area, is no lesa thfVI 
fourteen feet thick. Immense mountfun-masscs 
r.Misist of symmetrical bodies, between one fiw 
thousnndth and one ten-thousandth of an huh 
in di«raeter, articulated together in the form rf 
rings, as in chalk ; or of Jilender threads, as<iii 
limestone and the quartz of granite. An exact 
oovinterpttH of this curious stnicture in Ihe 
mineral kingdom is e\liihit«d in the vegetabis 
by the moldiness of paste, and in the antinal hf 
the creature called Gaillmiella fftruginea. 

The tripoli just menljoned consists almOBt 
entirely of an aggregate of nnimalcnles, in 
widely-extended layprs, without any comiectil^ 
medium. A cubic inch of this substance -wcn^ 


millioiiB of these gaillonellse ; the shield of each 
Goe weighing ahout one thousand one hundred 
and eighty-seven millionth part of a grain. At 
every stroke that is made with this polishing 
powder, several millions, perhaps tens of millions, 
of perfect fossils are crushed to atoms. 

Even where the shields cannot he separated 
in a distinct form, as in the consolidated nodules 
of various flints, opals, and other suhstances, 
troces of them and of similar remains are found. 
It is scarcely possible to imagine the countless 
multitudes of these beings which must have ex- 
isted in former ages, for their very coverings to 
have thus accumulated. It is peculiarly interest- 
ing to trace such occurrences in progress at the 
present time. Water, brought from a lake in 
the island of St. Vincent, has been seen crowded 
with the shields of races of animalcules at pre- 
sent inhabiting it ; and the mud which is being 
deposited abundantly at the bottom of the lake 
IB stated by Dr. Carpenter, to whom we owe 
the fact, to be almost entirely composed of 

Some remarkable appearances of the ocean 
are to be traced to these Uttle creatures. In the 
voyage of the " Beagle, on the coast of Chili, 
a few leagues south of Conception, the vessel 
one day passed through great bands of muddy 

water ; a degree Bouth of Talpara'iso the same 
appearnnce was slill raore extensive. Some of 
the water having been drawn up in b glass, it 
was found to be filled with living heings. Tbdr 
shape was oval, and contracted by a ring round 
the middle, from which proceeded the organs 
of motion ; it was difficult to examine them, 
for almost the int^tunt motion ceased their 
bodies burst. Sometimea both ends buret iit 
once ; somelimea only one, and a quantity o£ 
coarse brownish matter was thrown out. They 
were ei:ceedingly minute, and quite invisible to 
the naked eye, only covering a space equal to 
the square of the thousandth of an inch." "In 
one day," adds Mr. Darwin, " we passed through 
two spaces of water thus staiiied, one of which 
alone must have extended over several square 
miles. What incalculable numbers of th*M 
microscopical animals ! The color of the water. 
as seen at some distance, was like that of • 
river which has flowed through a red clay 
district ; but, under the shade of the veesel's 
side, it was quite as dark as chocolate, Tia 
line where the red and blue water joined was 
distinctly defined ; the weather, for some dv^ 
previously, had been calm, and the ocean 
abounded, to an unusual degi-ee, with Uving 
crefitures," The Luminous ap^eaisnca ^i^fnHi 


IB also partly accounted for by innuiuer- 
ide multitudes of phospboresuetit animalcales. 

In Sweden, on tliu aliores of a Iske near 
inea, araet quantity of extremely -fine matter 
, found, much like flour in appearance, and 
died by tbe natives mountain meal ; it is used 
t food, bwng mixed with flour, jind is nutri- 
cniB. But nrliat is tliia mountain meal when 
lined by the microscope ? Nothbg more 
the shelly coverings of certain animalcules I 
kB tlie animals perish, these coverings uccumu- 
ite from age to age at the bottom of the waters, 
Dd form a deep layer. This, drying on the 
liore, or on places which are no longer covered 
y water, assumes llie appearance whence it hag 
■ names, each partiulc being the relic of a 
ticroscopic animal,* 

The minuteness of some animalcules is almost 
loonceivable. Under the most poiverful mi- 
roscope, they appear only as moving points, of 
'hioh, by the use of the micrometer— an inatru- 
lent for measuring very minute bodies — eight 
ondred thousmid millions are calculated to 
ccupy a cubic inch of the water in which they 

oR«4der8 desirnua of furtlior information on tbis 
itject, ma; lnj reforred to " CuriositieB of Animttl 
A, wilb ivceDt DiscoverivB ot tVie 1A.\niovso^!' 
btdbjtbe IteligioaB Ttaot aoeifii,; . 



are found. Sup<;rior instruments, in rcfioeibnit 
aud accuracy, would probably disclose creatnra 
far inferior in sjee. Let it not bo supposed 
tliat such Etatements are citrnvftgant and hase- 
less. These are facts, which have been repeat- 
edly observed ; nnd, startling as the statement 
may be, it is proi'ed thnt> a drop of wst^l', 
t«iiiuilcd by the smallest anlmalculeB, termed 
monads, (to which we have already allodedi) 
contains a number «quul to that of the whole 
liiunau population of Ihe globe. 

The p!teiiomena o/blooi!. 
The blood of man and of land animals is 
found by the microscope to consist of round rti 
globules, floating in a transparent w&ter Of 
serum. Dach red globule is made up of all 
smaller and more trauspai'eot ones, and eaeli 
of these ^ain, according to Leuwenhoek, M 
composed of six globules still more minut« and 
colorless, so that every common red globule a 
compounded of at least thirty-six smaller ooMi 
The diameter of a common round globule of 
human blood has been found to be equal to the 
omj thouBaiid nine hundred and fortieth part if 
an inch. In order to view the blood with a 
microscope, take a small drop of warm blood as 
i from the vein, and, witlt the tip^^Jhk 

'fcair peacil, spread it as thinly 

idip of glass. It m»y also be diluted with a little 

'Warm water. 

CWcwiatioa. of tjus blood. — This wonderful 
(phenomenon, the esisteuce of which was first 
'ascertained by the celebrated Han-ey. about 
the year 1610, was never actually witnessed by 
Um, as miuroscopes were at that time 
known. As regards microscopic life, it appi 
to hare been first discovered in the water- 
by Mr. William Molyneaux, in the yenr 
Leuwenhoek, so much famed for Lis ekUl, has 
given many illuHtmtiona and descriptions of the 
method of emmlnmg it in eeis and small fishes. 
In order to observe the blood circulating in the 
reins and ai'teries, such small creatures as by 
their transparency permit us to look through 
tiidr external cuticle, and see what passes 
within tliem, arc &lt6sl to be used. Such are 
the frog, the water-ccwt, tadpoles, ctile, spiders, 
mi some other insects. The transparent mem- 
faiane between the toea of the hind foot of a 
frog, is the object most commonly selected for 
riewing the circulation of the blood, and in 
this it may be seen distinctly and beautifully, 
loth in the vems and arteries. A more sti-iking 
xt than (his can scarceVy >ia 'va«.igms&, tst 
more calculated to fiU ovit tooAs --s^ ^- 


n of ihe divine skill manifested in ev«y 

part of the organisation of the crentures of GwJ. 

Fig. 46 exhibits the vesseb in which this tip 

culation is performed, a a are the two toee of 

n frog's hinder foot ; b, the thin memhiane be- 
tween the toes, extended ; o c, the trunlu of iIh 
arteries: d d, the trunk o( avevn-, -t^,&ttenei 
<orf reina in the £dq membiane, VaV *w >i 


[es cireulatiag through them. The larger 
arteries are distinguishable by a protrusion of 
the blood at each contraction of the heart, 
whereas the current passes through the veins 
With an equal and Tinmtennitting stream. In 
the finer and extreme branches of the arteries 
this difference is not perceptible. The circula- 
tion of the blood may also be distinody seen in 
a Bmall tadpole, about an inch or three quarters 
of an inch in length. This creature generally 
lies quite still under the microGcope, and the cir- 
culation is Eeen in the vessels of the tail, in the 
fins on each side, and near the head. M. Leu- 
wenhoek tells US', that in the tail of a fish not 
more than half an inch in length, lie haa seen the 
blood running towards the extremities through 
arteries, and returning back again through veins 
wluch were evidently a continuation of those 
arteries, and of the same diameter with them. 
Hb remarks, " It is easy to conceive how smaU 
ihe tail must be, and yet in it there were sixty- 
eight vessels which carried and returned the 
lilood, and these vessels were far from being the 
most minute of all, How inconceivably numer- 
ous, then, must the circulaluais in, the whole ha- 
mui body be I" 



DeeerijJl'OH of the parts of some small ammalt, 
(IS seen in- the microscope. 
The flea. — This uflpopular little animal ap- 
pears a very beautiful and curious creature when 
examined by tbe microscope. With a common 
compound glass, it may be magnified to the ex- 
tent of eight or ten ijiches in length and a cor- 
responding breadth. It is adorned 'with a curi- 

ously-polished coat of armor, or iiard shelly 
Boalea, neatly jointed and folded over each other, 
and studded with long spikes, somewhat like the 
quills of a porcupine. Tbe general appearance 
of the animal is that of a beautiful piece of rt- 
riegated tortoise-shell. Its neck ia finely arched, 
and in shape resembles a lobster's tail. Its head 
is furnished on each side with a beautiful, quick, 
•nd round black eye, behind which 


unall cavity, ia which moves a thin film, with 
many transparent hairs, forming, as is supposed, 
ts ears. From the fore part of its head proceed 
iwo little jointed hairy horns or feelers, a and b, 
Ig. 47. Between these and its two fore legs, 
3 D, is situated its piercer or sucker. This in- 
cludes a pair of darts, which, after the piercer 
bas made its entrance, are thrust farther into 
the flesh, to make the blood flow ; thus is formed 
that round red spot, with a hole in the centre 
3f it, called a flea-bite. Besides its feelers, this 
insect has six legs, four of which are joined at 
the breast. When the flea intends to leap, it 
folds up its six legs together, and then throws 
them all out at the same instant, and thereby 
exerts its whole strength at once, so as to 
carry its little body to a considerable distance. 
The legs have many joints, from each of which 
proceed long hairs or bristles ; and each foot is 
famished with a pair of hooked claws or talons, 
that the insect in leaping may cling the better 
to what it lights upon. It is interesting to no- 
tice the surprising agility with which this little 
creature can leap, as many experiments have 
proved, a hundred times its length. Its pro- 
digious strength is no less remarkable. It has 
been made to draw loads, hundreds of times 
heavier than its own bulk. Its muscles must 


therefore be very strong and vigorous. Hoff 
weak and sluggish, ia proportion to Iheir siie, 
must be the liorse, tlie cumel, and even the ele- 
phant, when compared with this puny insect! are male and female, and they pass through 
the same chftnges as the sillcworm. When their 
oggs are hatched, they come out in the shape of 
worms or maggots ; tliey afterwards put on tba 
chrysalis or aurelia form, and when they isaoe 
from this etatc they are perfect fleas. 

2, Mites. — Mitea are very Gmall creature* 
foimd in cheese, meal, and otlier substances. To 
the naked eye they appear like diist in raoticm; 
but the sharpest eye is unable to distinguiBh 
their parts without the assistance of glasses. 
By the microscope we. perceive that they are 
aoimalB, perfect in all their members, and that 
they perform all the offices of Hfe in as regular 
a manner as those wliich are ten thousand times 
larger. The mite is a crustaceous animalcule. 
It has a small head in proportion to its body, a 
sharp snout, and a mouth like that of a mole. 
It has two smnii eyes, and six and sometimes 
eight legs, each of which terminates in two 
booked claws. Each leg has six joints, sur- 
roimded with hairs. The hinder part of the 
body is plump and bulky, ends in an oval form, 
and ia coFered with a few long hairs, aomft flf 



tbem as long as the animal itself. Other parta 
of the body and the head also have hairs. The 
female lays eggs, and the young ones issue forth 
with all their members entire. The diameter of 
a mite's egg is about the diameter of the hcur 
of a man's head, and m hundred such hairs are 
equal to the length of an inch. It would take 
ninety-one million, one hundred and twenty 
thousand of these eggs to equal in size one 
pigeon's egg. The mite is very voracious, and 
is exceedingly tenacious of life. It has heen, 
kept alive for months together without food. It 
is represented in fig. 48. 

3. Some curious species of small crustaceons 
animals are found in the water of ditches. Two 
of the most remarkable are represented in figs. 
49 and 60, in the posture in which they swim. 
Their legs are somewhat like those of shrimps 
or lobsters, but of a more curious structure. In 
size they are less than a very small flea. They 
carry their spawn either on the tail or in bags, 
as in fig. 49. They appear to have only one 
eye, which is placed in the middle of the fore- 
head. They are sometimes found so transparent 
that the motion of their intestines is distinctly 
seen through the microscope, with a re^lar 
pulsation in a part supposed to be the heart 
Another animal of a singular iorm \& T^^xosu^uted 


fig. 51. It is found in infusions of vegeta- 
bles, and in water that has stood some time un- 

ered. This little creatine is in its middle 
atate ; it was lately it worm, and will soon be- 
come a gnat. It has a very large bead in pro- 
portion to its body, wbich is covered with a 
Bhell. It hfts several tufts of hair, two horns, 
eitd a large mouth; The hinder part of the 
belly consists of eight joints, from the midst of 
which, on either side, issue small bristles. The 

. is divided into two parts, very different in 
their structure. One of them, a, has several 
faifts of hair, hy which it can steer itself in the 
water as it pleases ; the other part, c, appears 
to be the ninth division of its body. Fiom the 
part to the head appears a colored intestine, 
through which the peristaltio motion is discerni- 
ble. After having lived in the water its allotted 

le, a remorbable change ensues. It assumes 
a different form, and having cast off skin, eyes, 
horns, and tails, it appears the insect of a dif- 
ferent element. The most beautiful and elegant 
plumage adorns its head, its wings are curiously 
friaged and ornamented, it springs into the air 
with astonishing freedom and swiftness, and the 
creature which a few minutes before was an in- 
hatdtant of the water, wovild. uiaw \a d\:Q«fted 
if it were plunged into it. 


4. The etinga ofanimalt. — These are sbarp and 
penetrating inBtruments, iritli which the t^ls of 
wasps, bees, hornets, and some other insecta are 
fumiahed, for defending themselves against thwr 
enemies. The sting of a bee and of a wasp are 
similar ; it is a homy sheath which includes twfi 
bearded durta. The sheath tnpers to a very fiu 
point, and near it is aa opening, tlirough which, 
at the time of stinging, the darts are protruded, 
One of them is a liLlle longer than the other, 
and they penetrate alternately deeper and deeper, 
taking hold of the flesh by hooks, till the wbole 
stzng is buried in the woiwd, when a veoomoiu 
juice is injected frona a little bag at its root, 
which occasions an acute pain. The ehealh 
with its darts is represented in fig. 52. If du 
wounded person starts before the bee can diaof 
gage the sting, it is left behind sticking in the 
wound ; but if he can have patience to stand 
calm and unmoved, the bee brings down the 
lateral points, and clinches them round the shaft 
of the daj-t, by which means the weapon is re- 
covered, and less pain is given to the sufTerer. 

5. The hairs of animals. — These supply 
materials also for microscopical observation. 
All bail's are found to be tubular, that is, they 
consist of extremely minute tubes or pipes. 
There is a great variety in the hairs of 


anirruJa when examined by the microscope. 
H«ia taken from the head, the eye-brows, the 
nostrils, the beard, the hand, and other parts of 
the body, appear dissimilar, both in the roots 
and in other parts, varying as plants do of the 
same genus but of different species. They have 
each a round bulbous root, which lies very deep 
in the skin, and imbibe their proper food from 
the adjacent humors. The hair of a mouse 
seems to be one single transparent tube, with a 
pith made up of a fibrous substance running in 
dark -lines, in some hairs transversely, and in 
others spirally. A bat's hau*, especially that of 
the Indian bat, presents a most beautiful struc- 
ture. It is remarkable for a series of scale-like 
projections, arranged in the form of a whorl 
around the central part, or shaft. In some hairs, 
the succession of whorls resemble very much a 
series of conical bags, placed one within the 

6. Scales of fishes. — The outside coverings of 
fishes are scales, formed with inconceivable 
beauty and regularity, and ai-e very curious ob- 
jects for the microscope. Some are long, some 
round, some square, some triangular, and others 
of all imaginable shapes. Some are armed with 
sharp prickles, as those of the perch and the 
sole, while others have smooth edges. There is 


he beRj, T 

likewise a great variety of scales, 
same fish, for the scales taken from the 
, the back, the sides, the bead, and other purtfl, 
are different from each other. There is no woA 
of art we can compare with their bcautJfuI me- 
chanism. The finest needle-work Vhicli liM 
ever been wi'ought cannot for a moment be put 
in competition with the beautiful net-work, and 
interwenvioga, and divarications which appear in 
the contexture of these scales. The scales of 
eels arc among the most i-emarkable. ISamj 
imagine that these iah are without scales, on BO- 
count of their being firmly imbedded in a thick 
epidernial mucu$. In order to procure them, a 
sharp knife must be passed underneath the ep.' 
dermal layer, and a portion of it having been 
raised, a few scales may be detached. They are 
of an oval figure, and rather softer than those of 
other fishes. To view the scales of any fish to 
advantage, they should be soaked in water for a 
few days, and then carefully rubbed, to clean 
them from the skin and dirt which may adhere 

7. The dust m llie mngs of {he wio(A and 

butterflij. — On the "nings of these insecta ia a 

fflealy dust, or down, which is n beautiful object 

for the ;oicrosOftpe. The \inft& wtv '*» ■aoiwto 

particles have been used of \a(e V<*« ^'^ \»si!to% 

[eflniDg powers of simple lenses and acbro- 
: combinaljons. The dust is easily removed 
tom the wing by gently pressing it upon on ordi- 
laiy slider, or upon a thin piece of glass, to j 
'hich it will firmly adhere. It consista (^^| 
Mthers of different shapes, mtli ten or twelfft^^B 
iats on each, proceeding from a point, like the ~ 
IB^ of a circle, and terminating in well- defined 

Rilnta at the other end. Those in one part of 
e wing often differ from those in anothcjr part 
of it. On its fringes, and near the thorax and 
ihoulder, they have the appearance of hair rather 
thaa of feathers. The feathers of the moth are 
longer and more beautiful than those of the but- 
terfly. But when some quantity of dust from 
the wing of cither is laid upon a slider, or a thin 
l^ltp of glass, under the compound achromatic 
jnicroscope, with a power which will make the 
feathei-9 appear two or three inches in length, 
tbey present a variegated and splendid appear- 

8. The ei/es of insects. — In all creatures, the 
e ifl a atriking object ; but the eyes of insects, 
so peculiar as to excite our highest admiration, 
'KOXAd have been unknown to us without the as- 
sistance of the microscope. On the heads of 
ieellea, bees, w^sps, coTOi!noafiK.a, M\\a, iiasj^- 
lea, batterSies, aod other inaeiU, tfta-"^ '^^'V**- 


ceived two protubernnces, which contain a pro- 
digious number of small transparent hemispheret, 
placed with the utmost regularity in lines cross- 
ing each other, and resembling lattice-wwk. 
These are a collection of eyes, so perfect^ 
smooth and polished, that, like so ouinj mirror^ 
they reflect the images of all external objects. 
The image of a. caudle or a window<sash msy be 
seen multiplied to an astonishing exteal. Fignre 
£3, taken from Adams's " MlerograpMa," exhi^fgi 

a representation of the eye and some other parU 

of a di'one fly. Tlint half of the heraispWe*, 

c D E, c D £, which looked lowaxiavvs V^^ww^ 

observed to be smallir Omvu fcc o<k« V«K, 

c E, whicL looked upwards and side- 
The surface of these heraisplieres wns bo 

I EiBODth and regular, tliat in each of them the 
as nble to discover a landscape of 

I those objects which lay before the window, part 
of which was a large tree, whose trunk and top 
be plainly sow. These little hemispheres have 
each a minute transparent lens in the middle, 
which has a distinct optic nerve ministering to it. 
While other aniraals are obliged to turn their 
^es to objects, the fly has eyes nearly all around 
it. The number of the hemispheres or globules 
in the drone-fly was reckoned to be fourteen 
thousand, being seven thousand in each eye. 
Leuvenhoek reckoned six thousand two hundred 
and thirty-wi in a silkworm's two eyes, three 
thousand one hundred and eighty in each eye of 
a beetle, and eight thousand in the two eyes 
of a common-fly. In a dragon-fly he reckoned 
in each eye twelve thousand five hundred and 
forty-four lenses, or in both twenty-five thousand 
and eighty-eight, placed iu a heitangulnr position, 
each Ions having six others around it. A por- 
tion of these transparent hemispheres may be 
seen by allowing the rays of the svm to shine 
upon the eye of a dead fly, when placed under 
B microscope on a slip of gWa, 



Vegetable substances. 

Vegetable nature presents to us an imi 
field for the employment of the microscop( 
innumerable beauties and wonders which, 
out this instrument, would never have bee 
covered or imagined. Our limits prevent va 
doing more than briefly noticing a few exai 

1 . The farina ofjlowers, — This appears 

naked eye a kind of powder, which is fou 

the pendant tops of almost every flower 

color is various in different flowers, but its 

Q ture is invariably the same in plants of the 

■ ti . species. The microscope has shown us thi 

powder, in former ages supposed to be a 
excrementitious and unnecessary part o 
plant, is produced with the utmost care, i: 
sels wonderfully contrived to open and disc 
it when it becomes mature ; and that thei 
pistil, or seed-vessel, in the centre of the £ 
ready to receive the minute grains of this 
der, either as they fall of themselves, ( 
blown out of their httle cells. From nun 
* : experiments, it is found that on this the fe 

of the seed entirely depends; for if the 
vessels are cut off* before they open and 
shed their powder, the seed is improlific. 
intended for the nucroscope, the farina sho 

i t 

■L . 


i . • 

■ I ^ 

gfttliered duiing a diy sunny day, and gently" 
brushed off witli a soft hair pencil on a, pieco of 
whiK paper, and put upon a elip of glass to be 
applied to the microscope. A collection of tli6_ 
most remarkable kinds of farina of difTercnt flon^J 
era will amply repay the care and attention of B^| 
who delight to examine the works of God. j| 

2, The leaves of plaiils and Jlowera. — The 
leaves of trees, shrubs, or flowers, are found to 
be full of innumerable ramifications, which con- 
vey the perspirable juices to the pores for their 
discharge. The fibres of the leaf do not stand 
in even lines from the stalks, but always in an 
angular or circular position. Tliis arrangement 
tends to the more erect growth and greater 
strength of the leaf, and also to the security of 
its sap. M. Leuwenhoek, having torn a leaf of 
box to pieces, that he might examine it thor- 
oughly, computed one side of it to contain one 
hundred and seventy-two thousand and ninety 
pores ; and as the other side had the same 
number, the total amount of pores in a box leaf 
.was thus ascertflincd to be three hundred and 
forty-four thousand one hundred and eighty. 
Leaves in general exhibit a great variety of beau- 
tiful ramifications. Tbe back of a rose-tree lea^ 
but espedally of a sweet-brier leaf, looks aa '^m 
^pered with silver. A sag^e leaf appears jl 


if tasseled with white silver thrums, and embd- 
lished with fine round crystal beads, fastened by 
little foot stalks. The little globules which ap- 
pear on these and other aromatic plants are sup- 
posed to give rise to their fragrance. The back 
of the leaf of the English mercury plant loob 
as if rough-cast with silver, and as if all the ribs 
also were set round with white transparent balls. 
Fig. 54 represents a magnified view of the sweet- 
brier leaf. Fig. 55 is the sage leaf magnified. 
The leaves of plants and flowers are indeed a 
striking comment on the words of our Saviour : 
** Consider the lilies of the field, how they grow ; 
they toil not, neither do they spin ; and yet I 
say unto you, That even Solomon in all his glory 
was not arrayed like one of these." Matt. vi. 
28, 29. So beautiful and delicate is the fabric 
of the leaves of plants, and especially of flowers, 
as seen in the microscope, that it infinitely ex- 
ceeds in these respects all the finest pieces of 
workmanship that art has ever produced. The 
threads of the most delicate ribbon, under the 
microscope, look hke the coarsest rope-yam, and 
the silk itself like the substance of a conunon 
door-mat. But the more we magnify the leaves 
of plants, the more do we recognize the hand of 
Him who fills the universe with light and every 
Aower with beauty. 

THE MICB":*^"^^ 

113 OBJtUIB' 





3. Transverse sections of plants, — ^These sec- 
tions are procured by cutting a small branch 
transversely with a very fine sharp instrument, 
so as to take ofif a slice nearly as thin as the hu- 
man skin, which then may be viewed as a trans- 
parent object ; while the air vessels, sap vessels, 
and pores of the wood, will be seen in their 
variegated figures, incalculable numbers, and 
beautiful arrangment. The writer has several 
of these sections, one of which he can never 
behold without the gi-eatest admiration. It is 
little more than a quarter of an inch in diameter. 
It consists of a number of concentric circles or 
divisions in its diameter, with an immense num- 
ber of radii proceeding from the centre to the 
circumference, and pores, or sap and air vessels 
of different sizes, distributed in beautiful sym- 
metrical order throughout the whole. From a 
calculation made, it appears that there are not 
less than one million two hundred thousand 
pores, or the openings of tubes, contained within 
its circumference. And all nature is full of these 
" marvelous works !" 

The following figure represents a portion of a 
transverse section of the root of mallows. The 
diameter of the section was about three-eighths 
of an inch, and the one-eighth part of that sec- 
Uon was cut out from it, and placed imder the 

IHB >UCIlOfiC01-£ AN'D ITS OfiJKlTS. ltJ3 
He. K. 

* * ft * 

microscope, wlien it appeared as represented m 
the figure a s shows the skin c d the bark, 
or all that part of the root which answers to It 
E r, the common Ijmphcducte , a n, the pithy 
part of the root ; i k, more lympheductsi in both 
which the black holes arc the air vessels. It is 
Dext to imposeible, however, to represent in an 
engraving alliba openings or vesaela which ap- 
pear in the section of a plant, when viewed 
through a powerful microscope, as new apertures 




are seen by every augmentation of the lighl 
I power of an achromatic glass. It may ak 

observed, that the configuration and the nui 
of openings or vessels are all different from 
other in the roots and branches of different t 
(\ so that in this respect, as well as in every o 

there is an immense profusion of beauty 
variety in tlie works of God. 

A great number of other microscopic ol 
might have been described, had our hmited { 
permitted, but we shall briefly mention onl; 
following. By the microscope it has been 
covered that there are scales on the human 
so small that, according to the calculatio 
Leuwenhoek, two hundred of them may be 
ered by a grain of sand. The perspirable 
ter is supposed to issue between these 8< 
which lie over the pores through whicl 
watery humors exude. The pores of the 
are exceedingly numerous. If a slice of 
upper skin be cut off with a sharp razor, as 
as possible, and a second slice from the 
place be immediately applied to the micros 
innumerable pores will be perceived. M. 
wenhoek supposes that there are one hui 
pores in a line one-tenth of an inch long, 
inch will, therefore, contain one thousand 
row, and a foot twelve thousand. Accordii 



. t ■■ 


. "if.: ' 

.-» V 

y ■ 

oompuLaticm, a foot square must have in it 
one hundred and forty-four niilliona of pores ; 
and if tlie superficies of a middle-sized man be 
fourteen square feet, tliere will be in his skin two 
thousand and sixteen millions of pores. If the 
band be well washed, and examined ^vith a mag- 
nifying lens, in the palm, or upon the ends or the 
first joints of the thumb and fingers, innumera- 
ble ridges, parallel to each other, will be found. 
On these ridges, pores may be perceived, lying 
in rows ; and when viewed through a good glass, 
ev«ry pore seems a little fountain, with the per- 
flpiratjon st^inding in it as clear as water ; if 
wiped away, the perapiration will be found im- 
mediately to spring up again. 

The threads with which a spider weaves its 
web are worthy of our attentive consideralion, 
on account of their extreme fineness. M, Leu- 
wenhoek, having dissected the body of the long- 
est spider he could find, and nicely examined 
each part, at ]ast discovered a vast niunber of 
instniraents, as they may be termed, from which 
the spider draws threads of various fineness ; 
these thread vessels he judged to be at least 
four hundred, lying, not close t(^ether, but in 
several distinct clusters. Having laid a spider 
on its back, so that it oovii ^uA ?,'OT,Vft-^"*&s*i- 
oiit, with a very fina pmt ot ^«\ts«B>, ». ■&:««£ 


that he perceived sticking out of one of the 
working instruments. . At the same time he saw 
a great many other very fine threads issuing 
from the insect's trunk, which, at the distance 
of a hair's breadth or two from the body, were 
joined together, and made thick threads. *Some 
of these filaments were so extremely fine as al- 
most to elude his sight, though he made use of 
his most powerful glasses. Hence it appears 
that the threads of a spider's web, which to the 
naked eye seem to be single, do really consist 
of several plies, some of which are so exceed- 
ingly fine, that Leuwenhoek thought that one 
hundred of them put together would not make 
one-hundredth part of the thickness of a hair 
of his head. Ten thousand, therefore, of the 
fine threads of a full-grown spider are not so 
thick as a human hair ; and if we add to this, 
that four hundred young spiders, when they 
first begin to spin, are not, one with another, 
bigger than a full-grown one, and yet that each 
of these spiders is provided with all the instru- 
ments of the old one, it will follow that the 
smallest thread of a young spider is four hun- 
dred times smaller than that of a great one; 
and if so, then four million of such threads are 
not so thick as the hau- of a man's head, a fineness 
quite astonishing, and beyond our conception. 


Test ohjecta, — About the year 1826, Dr. Gor- 
ing discovered that the structure of certain 
bodies could be readily seen by some micro- 
scopes, but not by others. These bodies he 
called test objects. In the course of his experi- 
mentsj he was led to the conclusion that there 
were two distinct powers in a microscope, name- 
ly* defining and penetrating, and that an object- 
glass might possess the one almost to perfection, 
and yet be totally devoid of the other, or might 
be perfect in both. At present, however, it is 
the opinion of the most celebrated opticians that 
the terms definition and defining power are the 
only expressions requisite to be employed to de- 
note the good or bad qualities of any microscope. 
The test objects now generally employed for 
ascertaining the merits of any achromatic com- 
bination may be divided into three kinds, namely, 
hairs of animals, scales from the wings and bodies 
of insects, and the siliceous coatings of recent 
and fossil infusoria, — those of the latter kind be- 
ing the most difficult of all to define. The fol- 
lowing fist contains a few of the test objects to 
which allusion has been made : — 

Hairs. — The Bat. — The hair which forms one 
of the test objects is obtained from the species 
of bat before mentioned, inhabiting some parts 
of India. The principal parts of the hair that 

fonn tt test of the defining power of a Iifllf-inch 
object-glass, are the delicate points, or scale- Kks 
projectjons, that surround the iipper edge of 
each whorl, which should be slioirn osoeedingly 
sharp. In some of the species of English bate, 
the whorls are arranged in a spiral form. Moim 
huh: — The hair of this little animal differs va.- 
terially both in structure and in size from tlutt 
of the bat. In some parts of the hair the in- 
ternal structure is cellular, there being three or 
more cells in each row,_the color of the hair de- 
pending upon the greater or less amount of the 
black pigment contained in the cells. Wlien 
viewed with a power of one or two hundred 
diarapters, all the light parts shoiild be shown 
distinctly from the dark, and the line of separa- 
tion of the two correctly defined. When viewed 
as an op»que object, tbis hair is veiy beautiflil. 
Hair of the demiestes, — This very remarkable 
hair is obtained from the larva of a small beetle, 
commonly met with in hacou, hams, and othei' 
dried animal substances. It is covered over with 
brownish hairs, the longest specimens of which 
should be selected. When one of these is viewed 
with a magnitying power of two hundred diame- 
ters, the upper part may be said to consist of a 
shaft and expanded extremity or head. The 
part of the shaft, x&xx tW V,«ed, la 


vided witli several larirer and more obtuse spines, 
forming u knob. This very beautiful hair i 
forms a good teat of the defining power of a 
half-inch object-glass. The hairs of Che r 
the rabbit, and the Bquirrel, are aiso used ps i» 

Scalei on (lie wiriffs or bodieg of incwf*.-" 
ffipparchta Janira, the common meadow brown 
butterfly. The scales of this butterfly conast of 
lon^tudbal stria;, with n number of brown spots 
of irregular shape. When the magnifying power 
is increflsed to one thousand two hundred diame- 
ters, tiie brown cells are made more evident! 
Poiitia Bratsicit.the common cabbage butterfly, 
— This scale, like that of the former, ia provided ol 
its free extremity with a brush-like appendage. 
Its striaj are longitudinal, and with a power of 
live hundred diameters, it appears to be com- 
posed of rows of little squares or beads. Sciiies 
of Podiira, the common spring twj. — The body 
and legs of these Uny creatures are covered with 
scales of great delicacy. The surface of them 
appears covered with immense numbers of wedge- 
shaped dots, an-anged so as to form both longi- 
tudinal and transverse wavy markings ; when 
minified one thoasaad two hundred dinmetei^ 
the scales are seen to stand out boldly from tl 
surface ; at ilio upper part of the scale, t 



also project beyond the edge. These insects 
abound in damp cellars, where they may be 
seen running or skipping on walls. Scales frcm 
a ffnafs toing. — ^These, when magnified five htm- 
dred diameters, exhibit very bold longitudinal 
bands or striae, which project beyond the end in 
the form of spines. In the membrane between 
the longitudinal striae there is sometimes an ap- 
pearance like the watering in silk. Scale of 
MorphQ Menelaus, — A scale of this splendid but- 
terfly, when magnified five hundred diameters, 
exhibits strongly-marked longitudinal and very 
delicate transverse striae, the former frequently 
bifurcating. A half-inch achromatic object-glass 
should show them readily. Several other tests, 
besides those above enumerated, have been dis- 
covered by modern microscopes, which our con- 
fined limits prevent us from noticing. 

CompaHson of the works of nature and art — 
There is nothing that more conspicuously dis- 
plays the perfection of the works of God than 
a comparison of them with the finest works of 
art. The contrast between the one and the 
other is exceedingly striking, and hiunbling to 
the pride of man. His best performances, when 
examined by the microscope, appear coarse and 
shapeless ; but the more closely and clearly we 
are enabled to inspect the works of God, the 


; apparent is their supreme excellence. This 
be exemplified by a few illuatratjons. The 
t of an exceedingly email needle, highly 
ihcd, when Tiewed with a high magnifying 
er, appears neither ronnd nor flat, but full 
olea and scratches, and as broad and blunt 
le end of a poker, and looks as if it had 
I hammered on the anyil. On the other 
1, the sting of a bee or of a gnat, the pro- 
is of a butterfly or flea, appear, when ei- 
led by the raioroscope, to be formed with 
most surprising beauty, and with exact regu- 
y. The sting of a bee shows a polish with- 
the least flaw, blemish, or inequality, and 
. hi a point too fine to be discerned; yet 
is only the s/aatk of instruments still more 
ed. The following figure represents n piece 

Eceedingly fine lawn, as it appeared through 
microscope. From the great distanced W 



tween its threads it looks like a lattice, and the 
threads themselves appear coarser than ropes. 
Compare this with any leaf of the forest, or 
grass of the field, under the same magnifying 
power, and a most striking contrast will be per- 

The small dot or point, which is generally the 
mark of a full stop or period, when greatly mag- 
nified appears to be rough, jagged, and uneven 
all round its edges, and very far from being truly 
round. The smoothest and most exquisitely-en- 
graved lines and points, when examined by the 
microscope, seem like so many furrows and holes, 
or like daubings on a mat made with a blunt ex- 
tinguished brand. On submitting to the micro- 
scope the edge of a very keen razor, it appears 
as broad as the back of a thick knife, rough, full 
of notches, and furrows, sharper in some places 
than othei*s. Compare these works of human 
art with the operations of a puny insect, directed 
.by instinct, or the wisdom and intelligence of its 
Creator, and the contrast appears most striking 
and admirable. A silkworm's web, examined 
by the microscope, appears perfectly smooth and 
shining, everywhere equal, and as much finer 
than any thread which the most dexterous spin- 
ner in the world can make, as the thinnest twine 
h smaller than the thickest cable. The web 


woven by a spider is still more delicate. Every 
thread of it is many thousands of times smaller 
than a human hair. In short, every minute hair 
and fibre on a flea, a gnat, a fly, and other in- 
sects, is not only smooth and beautifully polished, 
but, when magnified thousands of times, appears 
as sharp at the point as a needle. 

Thus smk the works of man when placed in 
comparison with the works of God. Wherever 
the microscope is applied, there beauty, order, 
and perfection are displayed. In all the innu- 
merable varieties of insects which fly through 
the air, swim in the waters, or crawl along the 
earth, symmetry, proportion, and uniformity, 
are perceptible. Their bodies, heads, wings, 
feet, and other members, are embellished as 
with rubies, diamonds, gold, silver, and pearls ; 
they are colored with azure, green, yellow, red, 
and vermilion hues ; yet in all there is nothing 
gaudy or incongruous. How unutterable the 
Perfection of which these are the creations ! 

Metlwd of using microscopes, — 1. In applying 
the microscope to use, examine in the first 
place whether the glasses be clean ; if not, they 
must be carefully wiped with very soft leather, 
taking care not to soil them with the fingers, 
nor to place them in an oYXvs^'^ ^^j^sa^ksoL. 
2, The object should be \ko\x^\» ^ ^^^»3l "^^ 


centre of the field of view as possible, for th^e 
only it will be exhibited in perfection. In a 
compound microscope, the eye should be moved 
up and down till the situation is foimd wh^e 
the largest field and the most distinct yiew of 
the object are to be had. 3. A small mini- 
fying power should always be first used, by 
which means an observer will best obtain an 
exact idea of the connection and situation of the 
whole. In general, it may be remarked, that 
there is no advantage in examining any object 
with a higher power than what shows it dis- 
tinctly. A moderate power affords a greater 
light, and shows objects more clearly, than the 
highest powers, although sometimes these are 
required. 4. The eye should be protected 
from all extraneous light, and should not re- 
ceive any but what is transmitted through or 
reflected from the object. 5. According to Sir 
D. Brewster, the best position for microscopical 
observations is when the observer is lying hori- 
zontally on his back. This, he says, arises 
from the perfect stability of his head, and from 
the equality of the lubricating film of fluid 
which covers the coniea. The worst of all 
positions is that in which we look downwards, 
vertically. If we stand up and look horizon- 
tally, parallel markings or lines will be seen 



most perfectly when their direction is vertical, 
heing the course in which the luhricating fluid 
descends over the cornea. 6. Every part of 
the view should be excluded except that which 
is under immediate observation. 7. In every 
case of microscopical observations, homogeneous 
yellow light, procured from a monochromatic 
lamp, should be employed. 8. In viewing 
opaque objects, an opportunity should be taken 
wheir the sun shines of making his rays strike 
upon the surface of the object. In this way 
we may view to advantage the body and the eye 
of a fly, the fibres of a peacock's feather, and 
similar objects. Or, a broad convex lens, about 
three inches focal distance, may be so placed as 
to throw the light of a lamp upon the object, 
the surface of which would then be distinctly 
visible. The best mode, however, of viewing 
opaque objects is by means of a contrivance 
called the Lieberkuhn, from the name of its 
inventor. This consists of a concave silver 
speculum, highly polished, in the centre of 
which is placed a magnifying lens. This specu- 
lum has a small hole in its centre, and may be 
applied immediately below the object-glass of a 
compound microscope. For this purpose the 
speculum must be placed at the end of a small 
tube, to slip over the tube which holds the 


object-gbse. The hgtii proceeding fiom tlie 
minor faUs apoo tlie specalnm, and is reflected 
peqiendicnlarij on the upper surfiMe of the 

It seems almost trite and needless to sav, 


that the discoTeries which we have been con- 
skieringy equally with those of the telescope, 
demonstrate the existence of God, and -teach 
us lessons of confidence in him, by showing us 
that there is rothing too minute for his notice, 
or too humble for his care. Why is it, then, 
we may inquire, that any should habitually 
live as if he could nowhere be seen in "the 
thinsfs that are made ?" Whv is it that he 
should be so Uttle thought of, acknowledged, 
and adored, when his glory is reflected by every 
object in nature — from the blazing sun to the 
atom which floats in its beam — from the moun- 
tain to the flower which blooms beneath its 
shelter — and from "the great and wide sea" 
to that drop of water which is as an ocean to 
the numberless and invisible creatures which 
it contains? To these solemn questions we 
have a reply in the words of the great reformer, 
Luther: "Had not man sinned," said he, 
**how would he have recognized the glory of 



God in all his creatures, and have loved and 
exalted his holy name ; so that in the smallest 
flower he would have acknowledged the al- 
mighty power, wisdom, and goodness of God !" 
Max has sinio:d, and therefore it is that *' God 
is not in all his thoughts." 

It is sometimes said, as if it were a maxim 
not to be disputed, that *' nature leads us up 
to nature's God." It is not true. Man has 
SINNED, and he " will not seek after God," till 
he knows more than nature, with all its light, 
can teach him. He is surrounded, as we have 
seen in the preceding pages, by proofs of wis- 
dom and power, infinitely surpassing the highest 
efforts of human intelligence and skill. This 
may be confessed. There may be admiration, 
and even gratitude, awakened by these displays 
of the divine perfections, and yet there may be 
no knowledge of God. Such a recognition of 
him is better than atheism, better than indif- 
ference, better than absolute forgetf ulness ; and 
yet it is compatible with mournful ignorance of 
the moral perfections of God, and with the ab- 
sence of all desire to retain him in the mind. 

Man has sinned, and he needs the word of 
God to teach him how ^vine holiness and 
justice may be harmonized with mercy in his 
pardon and restoration to bappinesa, Vla ^& 



conscious of estrangement and danger; and 
before he can know God in nature, so as to 
delight in him, he must know him in Christ as 
a Father, " reconcihng the world imto himself/' 
Has the reader, then, we may appropriately 
ask, been thus reconciled? If not, then, "as 
though God did beseech you by us, we pray 
you in Christ's stead, be ye reconciled to God. 
For he hath made him to be sin for us, who 
knew no sin ; that we might be made the right- 
eousness of God in him." 2 Cor. v, 19-21. The 
telescope and the microscope, whose revelations 
we have been considering, may be said to lend 
emphasis to this appeal. In the views which 
they open to us of the majesty of God, they 
proclaim his infinite power to bless those who 
love him, no less than his awful ability to 
punish such as obstinately reject the proclama- 
tion of his grace. How dreadful must it be to 
die at enmity with so great a Being ! — ^how de- 
lightful to be his adopted child, through faith 
in Christ ! Now, then, while it is the accepted 
time, may the reader, if he has not yet done so, 
close in with the pro£fers of his pardoning love ! 







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